 All right we are a couple minutes past so we'll get started now. My name is Nadia Kenner I'm a research associate at the UK Data Service based at UOM and this is the workshop named Mapping Crime Data in R, an introduction to GIS and spatial data. Before starting with the content I'm just going to run through some introductions but just to kind of let you know that this presentation will be treated as an introduction to the main topics and issues involved with GIS and mapping data. Now it isn't going to provide a huge array of information but it will detail what is necessary in order to understand the code demonstration on Wednesday. So I'm going to turn off my video and start with the slides. So today here is the content we're going to discuss exactly what GIS is. We then move on to look at spatial data versus non-spatial data. We then talk about the different types of maps that are available both reference and thematic and then we move on to a bit more of a complicated topic known as the projection methods and coordinate reference systems. Lastly we kind of draw on to a bit of a conversation about the challenges of mapping crime data. In the second part of this workshop which is being held on March 8th on Wednesday we will be doing our live code demonstration in our studio and these are some of the topics that we will be covering. We start with really like an explanatory of our crime data set looking at how to turn ordinary crime data into spatial data. We then talk about shapefiles and we move on to combining sensitive data in order to calculate crime rate instead of just the crime count. And there's also some fun interactive and fun extra topics such as how to make interactive maps. There's a little bit on jittering and there's also some information about how to use Google API to map data. But yeah let's get started with the workshop enough for the introductions. So what exactly is GIS? GIS stands for graphical information system. It can be defined as a computer system for capturing, storing, checking and displaying data related to positions on Earth's surface. It can kind of be seen as like a theoretical framework that allows for the creation and analysis of spatial and geographical data. I like to view this as a bit of an abstract platform that tends to integrate data onto a map using various methods. Now GIS is present in almost every field and every organization as it's a way to share information and to solve complex problems around the world. The biggest benefit I would say is allowing for trends and patterns to be studied visually which provides a new form of analysis. I'm going to give you a quick history about GIS but nothing too boring but it was kind of established in the 1960s by a pioneer named Roger Tomlinson and he was commissioned by the Canadian government to create a usable and efficient inventory of its natural resources. Now he tried various manual methods for overlaying environmental, economic and cultural variables onto a map but he found that these were all too costly or too timely. So he helped to create the first automated computing system and he was known as the father of GIS and from there we've had loads of research has developed this such as Laura and Jack Dangamond who developed the environmental system research institute also known as the ESRI or ESRI which is a really common software developed for mapping and spatial analysis. Geographical information systems, all data in geographical information systems are georeferenced meaning it has both attribute and a location and attribute kind of consists of what it is and a location is you know where it is and this has to be a known location. An example of a known location could be the latitude and longitude, you could have national grid coordinates or you might have things that a bit more of an implicit reference so things like an address, a postal code, a forest stand identifier, road names, census tract names, those things and an automated process called geocoding is then used to create this explicit geographic references from implicit references and these geographic references allow you to locate features such as businesses or forest stands or even events on the earth's surface for analysis. In relation to crime data the attributes that you might see in crime data could consist of where the call was received, who received the call or the type of crime that we have. Now there are various softwares available for running GIS, I tend to use RStudio and I've doubled in RGS a little bit but as you know this workshop will be using RStudio's on Wednesday demonstration and this is because I believe that there is an increasing amount of packages have become available for spatial analysis and mapping in the last couple years and it's also a really great tool for visualization and kind of just our interests maybe just me being a bit nosy I'm interested in to know what software you use the most. If you want to head back over to Mentimeter and you can just pop in your vote there what software slash have you slash do you use. I figured that a lot of people will be selecting RStudio's since you know hence it's the name of the talk if you do end up selecting other I'd be really interested to know what software this is if you could just leave a comment in the zoom chat that'd be great and I'd have a look at this when we're on a little break. This is partly me just being nosy but also it's kind of nice to get general consensus. Definitely got the majority sitting on RStudio which is no surprise we'll just give that another 20 seconds or so to let to let votes keep rolling through so votes have kind of come to us still so we'll move on for that thank you again for participating. So how exactly is GIS used? Esri or the ESRI however you prefer to say it they summarized 60 uses that I found really interesting this is to identify problems, monitor change, manage and respond to events, perform forecasting, set priorities and to understand trends and I think this provides a really useful kind of set of uses especially related to crime data. So one example that I want to talk about related to identifying problems but kind of addresses them all was an example on the ESRI website and they showed how GIS addresses the inequality of urban renewal and this introduces us to the term redlined maps. In in 1936 there was a company called the HOLC which was a home owner's loan company and they hired real estate accesses to create color coded security maps. These maps use a rating system to assign grades to neighborhoods reflecting the residential security. Basically it shows which neighborhoods are more risky and therefore less likely for banks to loan from. Now back then you can kind of imagine who was making these these maps you know probably older white males maybe more established maybe higher class but the colors in this map represent different classes so the green represented upper class, blue represented white collar class, you had yellow which was the working class and then you have that red which is the lower class. Now funny enough these red areas were actually marked as hazardous as they were home to foreign-born people, black people, lower class people and this is where the term redlining comes from. So what happened was lenders used these maps to determine which neighborhoods would be safest for financial investment but these assumptions were based solely on neighborhood descriptions not information about individual borrowers but with the advancement of GIS analysis and new data sets they were able to uncover relationships between these redlined areas and environmental conditions which included things like temperature and tree coverage and topography and there was a study conducted at the University of Richmond where they performed a text analysis on the keywords in these forms that made up the map and they were able to make the connection between environmental terms and their relationship to favorable or less favorable grade designations so like thanks to new advancements in high resolution data sets we can thoroughly examine the environmental legacy of these redlined neighborhoods and it helped to kind of expose the social effects and the physical environment. So here are just some of the questions that GIS allows us to explore with crime data you might be interested in where are the most vulnerable communities located for example if individuals want to use crime maps to safeguard their personal safety then you know avoiding areas of a high level of let's say street robberies and clearly a geographical representation of crime would be appropriate here what about if you were interested in why crimes occur in one area and not the other if you come from a criminological or sociological background you know that there are a lot of crime theories I've helped to explain this one theory is known as the crime pattern theory and it integrates crime within a geographical context that demonstrates how the environment people live in can pass through influence criminality so for example you know a suburban neighborhood can become a hotspot for burglaries because some homes have inadequate protection and nobody home to guard that property and you might want to visualize that distribution across certain areas what about how do offenders travel to the crime location in other words what is it about one specific place that convinces an offender to commit again there's been loads of reasons that kind of affect how far and oh how far an offender travels in fact there was a bit of research done by I believe Ackerman in 2015 that he found that violent crimes had a shorter medium distance to crimes and property crimes and then they were able to visualize this friend on a map or what about where are there more or less stop and searches then we would expect in relation to the distribution of crime so in this question you'd be comparing the actual distribution of crime and the level of stop and search in one area you can then start to question you know the necessity of stop and search you can start to ask questions about whether it's at all for crime reduction or crime detection or you know you can just start to question these police powers and have them visualized on a map so let's uh let's move on GIS are known to produce two broad types of maps these are known as reference and theomatic maps reference maps are used to communicate location on more static data points they use to pinpoint data on a map so this can be viewed as a description it's very like descriptive analysis we then have a thematic map and this is used to highlight a spatial relationship this is to study a theme within a map and this is where it becomes a little bit more explanatory here is an example of what a reference and a thematic map might look like on the left you see that a reference map they tend to just highlight natural patterns or synthetic features including the positioning in heights of mountains or the layout of bus routes and yeah this type of map is simply referencing hence the name what exists in our physical environment on the other hand these two me at the thematic maps highlight a spatial relationship it's how we map a particular theme to a geographic area it tells us a story about a place and is commonly used to map subjects like population densities health issues climate issues or even just distribution so sometimes the difference between reference and thematic maps can become confusing so let's have a look at an example in this example we have a tube map there was a project called lives on the line they they discussed that most government statistics are mapped according to official geographical units such as wards or lower layer super output areas and now whilst these units are essential for data analysis a lot of people are unfamiliar with what wards or lower layer super output areas actually are a bit uncommon to you know people who aren't in academia or research or statisticians so they decided to try a new method that use tube stops as their geographic unit as their unit of analysis and they aimed to show life expectancy statistics across different tube stations in London now looking at this map so did you say that this is a reference or a thematic map you know let's have a let's have a little look in one instance you might say that this is a reference map because they show the location of different tube stations and the location of each line you know they're highlighting a synthetic feature on a map however you might also view this to be a thematic map because you're mapping a particular theme to a geographic area in this case they're predicting life expectancy and other factors like poverty and median house prices to certain tube stations they're showing a spatial relationship between a social factor and a physical feature if you're interested the link to lives on the line it's found here it's also in the references and we'll send this out I guess at the end of the talk but this is a little interactive map that kind of helps you explore the differences and shows you just how a spatial relationship can be mapped out but to get you guys thinking a little bit about it yourself I've come up with a few scenarios and if you want to head back over to Mentimeter you can participate in this part of the quiz so I want you to have a think and decide whether you think that this scenario fits the description of a reference map or a thematic map so the visualization of road networks to improve road safety measures are a type of what map we'll give this a couple minutes a couple seconds and then we'll discuss the answer well done to help whoever voted no idea you like honesty in this workshop and that's absolutely okay if you have no idea I can understand that the two can be pretty confusing it seems that the majorities have stated that it could be both and I think I might just agree with you here because if you break this scenario down into two aspects right at first this might be said to be a type of reference map as we are simply pinpointing existing road networks onto a map right so we have a map that shows all the different road networks however this might also be said to be a type of thematic map as we're studying the existing road networks to then improve safety measures which can be seen as a type of like accident analysis so yeah we're studying spatially the relationship between road networks and accidents and this might then lead to you know the introduction of speed signs or zebra crossings or increased streetlight lighting in certain places but the point is they are mapping a particular theme to a geographic area we'll move on to scenario two the visualization of the earth's surface showing its elevation can be considered what type of map everyone's voting reference we've got another no idea if you like the honesty and we've got a good could be both we've still got a few votes coming in so we'll just let this roll out for another 15 seconds all right the votes are slowing down so I think I'll discuss what I think the answer is I would have said that this yeah this is a reference map because the visualization of the earth's surface showing its elevation is actually a type of topographic map and these maps refer to a graphical representation of the three-dimensional configuration of the surface of the earth so in short it's simply describing or showing where the earth's surface surface is elevated these maps are normally represented by contour lines so you might have seen these on a map before but you know the closer the lines the less height there is right and that's kind of just a description is pinpointing but for those that voted could be could be both you are onto something because you might also view the type of map as a thematic map research has suggested that studying a topographic map is a great way to learn how to match terrain features with the contour lines on the map so this include this could include the steepness of the terrain the shape of the terrain or whether it's above or below sea level so in this instance you might interpret that we are studying spatially the relationship of contour lines to the different features of the earth but at the same time it is kind of the way you use the map right so if you answered any of the options consider yourself to be correct well done either way the answer is open to debate it's the difference between mapping places and mapping data we'll move to scenario three so creating a map that shows the location of different species of birds in a particular area is an example of again reference thematic no idea could be both but the majority voting thematic this time interesting and we've got a few could be both maybe people are catching on with what I'm doing here we've got a couple references as well but we've got no ideas but we've got no no ideas so that's good I'll give it another 10 seconds there's a few more votes still rolling through sweet it looks like we are paused so yeah I think if you had voted thematic I would probably agree with you in this instance because this type of map is used to show the spatial distribution of the different bird species right it's not just indicating where particular birds are but it's telling us the distance between different birds and that is indicating more than just a description it's telling us more than just about the physical land so again all wants is here all right it can be considered reference it can be considered as thematic so congratulations to all and I think we've just got one more scenario and then we'll get to move on so in this last scenario navigation tools things like google maps city map city mapper or or ways or whatever do you think that these are classes of reference map or thematic map the majority of votes are sitting on a reference map we've got one vote thematic and again we've got more people saying this could be both which means you're probably catching on with what I'm trying to tell you here we've got about 23 votes in so I'll just give that another 10 seconds votes are still shifting but it definitely shows that the majority are sitting on a reference so again I would have agreed like immediately you might assume that this is an obvious type of reference map right as it's highlighting important physical features such as bus routes walking routes cycle lanes which are all needed for travel so it is just telling us where certain routes exist on a map which is very much descriptive however surprise surprise this might also be said to to be a thematic map right because reference maps portray a basic set of features as we've said like coastlines to range to transport routes but can we say that an app that plans your travel is a type of reference map because if it uses some sort of AI algorithm to get you to one place to another you know normally choosing you the fastest route or the cheapest route can we call this a thematic map instead since it's overlaying additional information onto our reference map and this is a really interesting debate actually and it kind of draws back to the father of GIS Roger Tomlinson he draws importance to analog versus digital maps and their place that they can have in GIS and recently researchers have considered navigational tools to be fundamentally different from both reference and thematic maps which kind of opens debate for the third category don't know what that third category is but there is some sort of like ambiguity around where navigational tools stand so it could be argued that all maps are navigational right just depending on how you use them the difference is that a digital map one that is specifically interactive like google maps and yeah and this is exactly what Roger did Roger Tomlinson did he couldn't overlay overlay his data on an analog map so you know he moved towards computation so yeah navigational tools doesn't have a correct answer yet there isn't a it doesn't 100% belong as a thematic nor does it 100% belong as a reference because it does tell us more than descriptions it tells us how to do something even though this isn't necessarily a spatial relationship so what can we sum up about reference and thematic maps as we said they fall into two broad categories but there are ways in which these types of maps overlap or share similarities I would say that almost every thematic map is also a reference map but not every reference map is a thematic map the decision is it's up to you you know it's not entirely necessary to define these in your work but it is important to know what type of map you want to make as these can be affected by the data you have and just to give you guys to keep you guys keep thinking I've got one more question on Mentimeter and yeah I want you to try and give me an example of any other types of map that you think shares properties of both reference and thematic descriptions you could type in your answer and they'll come up on the screen and then we can have a little discussion about any answers that appear so I'll give this 20 odd seconds maybe a bit longer that's great we have loads of answers coming through at the moment heat maps definitely heat maps are typically known as thematic maps but you know if this heat map has some basic information about the physical slash synthetic features of the land and honestly this will include you know or fit in the description of a reference map we have hotspot maps definitely this is a hotspot maps are a almost a key in in crime mapping it's a way to aggregate or discuss the like highest levels of crime in certain areas and again this definitely shows properties of both because we're showing the underlying spatial distribution and then you know providing references so where this has happened we've got cryding maps which I believe would definitely be properties of both as well I think this is where they used a sample data point to estimate the value of a variable over a continuous spatial filter yet that would definitely be considered both we've got world maps definitely would be considered both if they are colour coded by population size definitely because this is highlighting some sort of distribution we've got income maps would definitely be the same my screen is glitching a little bit so I'm struggling to see nuances that are appearing but we're getting the map showing what areas are farmlands forests etc yeah that I guess could be seen as a thematic I guess the point being is how you then use those maps because if this is a map that just shows descriptions about farmlands and forests rather than let's say the nearest distance from each of these farm plants then this might be seen as more of a reference map we've got income maps and social status definitely this is a way to kind of map variations in population we've got weather maps yes weather maps are really interesting actually and we discuss weather maps a little bit later on weather maps yes I would say are thematic because they provide data on more of a continuous level and show you you know the spatial distribution of different climate changes in a map so and yeah I think my screen is glitching so I'm struggling to see any new answers are appearing but I think I might have addressed all of them and on that note I think we're going to have a quick five minute break while I fill up my water bottle and I'll come back to ask any questions in the Q&A and then we'll continue on with the rest of the slide hey all I am back sorry about that I've also just seen a question in the Q&A which I will read out loud and it asks is there ever an instance where a map could be thematic but not reference it seems to me that a map by construction will need to have references and yes you'd be right that was kind of the the what I wanted to demonstrate in in the scenarios is that most reference maps sorry most thematic maps will have some sort of reference right because how else are we to understand the map imagine a map without any indications of what area we're in or what size um or what like what unit of analysis we're working in or imagine there are no street names or no city names then we're reading a map that doesn't tell us anything about anything but yeah thanks all for participating in that we've got loads of great answers and there are loads of great examples but we'll move on to the next part of webinar so we're going to move on to discussing what exactly spatial data is spatial data or geospatial data is a data frame that contains information about a specific location which can then be analyzed to better understand that location I like to see it as a representation of the real world it attempts to represent the physical features of the data in a accurate way now GIS then enables the spatial data to be processed and analyzed they kind of work hand in hand with without one you wouldn't be able to complete the other there are two types of spatial data that is the vector data and raster data these are two very different but common data formats that are used to store geospatial data so let's have a look at the differences between the two the break there's no break that was the front slide vector data now vector data is the most common form and it consists of points lines and polygons points are a pair of coordinates this is the exact location of where something happened so in relation to crime data this might be the location of where a robbery was reported we then have lines and lines extend the points and include at least two now this could be for example the street that that robbery was received on we then have polygons and polygons extend the lines and includes three or more points so this could be the area the city or the ward that that that robbery on that street belongs in you can kind of do this like you're zooming out from a map so you start really zoomed in you could be just looking at for example you know your house imagine you're looking at your house on a map that would be the point is then zoom out a bit and you'd be looking at where your house belongs on that street and you zoom out a little bit more and you will see that your house belongs in this city or this area you then have what is known as raster data and this is imagery or satellite data that are formed from a grid of pixels now this type of data has been described quote-unquote as a dumb electronic map image that is made up of a number of set of pixels the issue with raster data is that you cannot manipulate the information so you can't move a place name around and when you zoom into the map it can you know become quite pixelated and unreadable just like a photo taken on like a digital camera or like this image that you see on the screen but on the contrary raster data are well suited for representing data that changes continuously across a landscape or a surface yeah they provide a really good method of storing the continuity as a surface an example of this type of continuous data would be things like temperature or elevation or the weather map that was discussed earlier and each pixel will represent a different value or a different attribute within the overall range of values for that data now it's pretty uncommon to work with raster data early on in like introductory lessons so when we move on to our code demonstration on Wednesday we're mainly going to be working with vector data um and that's because we're not working with you know continuous data across you know surfaces so now we have a basic understanding of spatial data this is where we ask how do we actually pinpoint a location to a map and we do this through projection methods map projections try to portray the surface of the earth or a portion of the earth on a flat piece of paper map directions try to transform the earth from its spherical shape that is the 3d to a planar shape that is the 2d and that is how we actually pinpoint a location to a map and I hope my image my amazing image has been able to visualize that a bit for you but it's just about moving from the 3d to the 2d I have a bit of a bit of an example for you here imagine you have a football and you begin cutting it up with a knife now if you were to put this football back together into a sphere you would be all right there probably wouldn't be any issues it'd be a little bit bumpy but it would still fit back into a perfect sphere however if you tried to recreate this into a rectangle or a square or a triangle it just wouldn't fit together perfectly so these projections are simply equations that tell a mapping system the GIS how to populate a new area or new shape so if we wanted to create a rectangle we might have something like this where all the area is populated and this is what mapping systems do they reshape they flatten and then they make it manageable for us to then make maps on a 2d surface now you might already be thinking that surely there's going to be issues with this how can we make something 3d 2d that's never going to be perfect as we've discussed and you would be right because it's important to know that during this transformation during the projection methods the data can become distorted which leads to the misrepresentation of area, shape, distance and direction so although there are algorithms in place to control for this all four features are rarely preserved and I like to give this example where imagine you have a map projection as an attempt to reconstruct your face in two dimensions so some maps will get the shapes of all your features just right but maybe not the sizes maybe your forehead or your chin or your nose came about bigger or smaller you know other maps will get the sizes right but the shapes will be stretched so maybe your mouth has become wider than usual and you know some maps then try to preserve the distance but maybe the distance from your lip to your nose is shorter than what you're used to and so on so on so yeah you just have to think that squashing something from the 3d to the 2d is obviously going to affect these four factors call it that and yeah so it kind of all depends on which attributes you are willing to compromise some try to maintain the correct distance others the correct shape others the correct area but typically you aim to find a sort of sweet spot in the middle that balances all these factors and this is why you see projections that are individual to different countries so different regions and different districts and even different in countries have different projections that might distort or make a map look a little bit different and then what you're used to so there are actually three projection families this is known as the cylindrical conical and the planner and I'm not going to talk too much about them but as you can see by the image this is the way of making your projections and within each projection family there are hundreds to thousands of different types of projection and they're not necessarily they're not necessary to know but I do have an example of that shows how maps can become distorted due to different projection methods so I'm going to be using the example of the world map on two different projections just to kind of demonstrate you what happens in terms of this distortion so let's have a look at these projections right we have two maps here on the left we have a map that was made with the web the kater projection and on the right we have a map that was made with the gal peter projection now the kater uses something called I believe angular conformity and this is a type of projection from the conical family and on the right we have the gal peters which is a projection from the cylindrical family now the peter's projection is unique among world maps because the area ratios of all these continents are the same as they are in reality and that is greenland for example doesn't seem larger than africa whereas if you compare this to the micata you can see that greenland is as large if not larger than africa the micata projection tends to distort the size of continents and this causes what you might know as the greenland is larger than africa effects but the micata is able to stay true to their shape the geographically speaking the shapes are more important because it's far easier to change the scale of a map for different areas of the world than to adjust the length with ratio as you need to do with the peters additionally the micata tends to distort the longitudinal distances whereas the peters tends to like mess up the scale almost everywhere for both longitude and latitude and this is why the micata beats out the micpeters in the world of like maps and cartography and google maps itself uses a modified micata projection and this is typically what we see in as as the world map this is what we are used to even though like the micata's is is almost enlarging northern areas and they actually are so yes both projections have their strengths have their weaknesses but the choice of projection will typically depend on the specific needs of the analysis or the application so in general it's important to be aware of the potential for distortion in any map projection and to choose the projection that best meets the needs of the intended um analysis and audience because yeah obviously looking at these both looking at these maps both they portray very different perceptions of different countries so i hope that example's been able to show you the effects of projection and how distortion can be seen on a map we're going to just take another couple minute break here because i do like to break up my talks a little bit i hope that's okay we'll come back in i'll be back in approximately two to three minutes just stretching my legs and i'll be right back all right i am back i've stretched my legs feeling a bit better so we're going to continue on with the rest of this webinar um so yeah we've discussed our projection methods um the real question now is so we know how to move from the 3d to the 2d by our projection methods but how do we actually move from the 3d to the 2d how do these projection methods actually work and the move from the 3d to the 2d is done with the help of crs also known as a coordinate reference system now every place on earth is specified by three numbers our coordinates this is the latitude the longitude and the altitude and each number indicates the distance between some point and your fixed reference also known as the origin so once you have your coordinate reference system you can match this with a projection system that will enable you to move from the 3d to the 2d so let's have a look at the two types of reference system that exist we have geographic coordinate systems and we have projected coordinate systems now a geographic system is it defines where the data is located on the earth's surface so it defines the data um across the spherical globe across um that it defines the location of features on a model that is earth that is the globe that's the spherical shape we were talking about and as you can see in the image um we're represented by the angular units so this is the degrees and this is how you know that we're sat in the 3d we then have the projected system and the projected system tells the data then how to draw this onto a flat surface like a paper or you know computer screen and the projected system stay with me here it contains a geographic system but it converts this geographic system into a flat surface using the projection algorithms from the previous slides and in this instance you can see that in the projected system with those numbers at the bottom they are represented by meters and this is because this is a linear unit and this is because we are now on a flat surface so let's have a quick look at an example of a coordinate reference system that we might see online working with certain systems so as we said the projected system tells you how to draw this onto a flat surface and in this example at the top you can see that we are using the fuller projection system which i'm not entirely sure what the fuller is but the point is that it's using a projection system named fuller it's also associated by a wkid which is just under the word projection the wkid is or stands for the well known identifier and this is just a reference number that links up to a certain projection system when we scroll down when we look at the bottom you see that we also have a geographic coordinate system and this time the the geographic coordinate system remember tell you where on earth the data should draw in this instance we're using the wgs 1984 this is the world geodetic system and it's probably one of the most common forms of geographic coordinate systems that you will use at the same time we also have a wkid that's just that reference number and we'll see in our code demonstration on wednesday that we're going to actually be exploring this geographic coordinate system using our reference number typically you only need to enter the authority and the wkid that and that will call on the correct system um so i guess a few things to remember geographic coordinate systems fail to measure the distance and that's why the projected systems um become meaningful because this information is needed on a flat screen which can be done by various projection methods you know so when working with more than one form of spatial data it's important to ensure that the data is stored in the same coordinate reference system or they will fail to line up with the gis the graphical information system and the decision of which map projection and coordinate reference system to use depends on the regional extent of the area you want to work in um the possibly the type of analysis you want to do but most importantly is the availability of the data so that kind of gives a brief introduction summary to our projection systems and our coordinate systems but once we explore this in r you see how much how easier this is to understand once working with some practice data so once you've got all of this kind of um so once you understand what type of data you have whether that be vector or raster once you understand what a what coordinate system you need to work in you with them typically move on to your next stages in your in your research project in your analysis and this would typically involve the spatial analysis so to put into words that might be a bit more familiar spatial analysis is kind of like the method section of your paper this is where the bulk of the analysis would be and I've listed six what I think are very popular methods in crime um but in short spatial analysis refers to studying entities by examining uh evaluating and then modeling spatial data features such as the location the attributes and the relationships that reveal data's geometric or geographic properties we've already discussed some maps that involve some spatial analysis when we were looking at the differences between reference and thematic so we have a very brief understanding um I would say that spatial analysis is incredibly important for crime mapping because it can reveal patterns that may not be immediately apparent in the data um for example spatial author correlation is a technique that measures the degree to which crime occurs near each other in space so you can start to look at like neighboring relationships kernel density estimation is also a really common spatial analysis technique in crime mapping and this is a technique that creates a density map showing where crimes are most concentrated and this is um similar but key differences with hotspot analysis which we also spoke about today but yeah hotspot analysis is just a technique that identifies areas with high crime rates right and all of these types of analysis they then go on to allow law enforcement agencies and practitioners and policymakers to target these areas with more resources and more help so we're drawing on to our last topic of the talk which um what are the main challenges of mapping crime data I've listed a few on the slide and I'll talk through these and we'll give you the charts to kind of think about any others but uh most crime data or the most common way to get crime data is from the police dot um product UK website but using open police data can be criticised you know firstly police recorded crime provides point information through the use of GIS so that's that point data that we discussed as part of the vector data but the accuracy of this point data tends to be obscured by geo masking techniques um also known as geo privacy and this is just a way to protect the exact location of where a crime was reported in order to um protect the location privacy of victims which obviously makes sense because providing the exact location of where a crime was reported obviously can be risky for both victim and offender and uh I believe the technique used to do this is called jittering which um we do talk a little bit about in the code demo so what you think might have you know happened outside a school might not have actually happened in that exact location secondly uh police recorded crime are a known contribution to the grey figure in that they underestimate the actual number of crimes recorded and not just reported which reduces the accuracy of statistical models due to missing data um and you know this isn't something that can be overcome in mapping techniques but there are ways to minimise this like um there are reliability of missing data and you know there are also some conceptual issues surrounding its definition of certain crime types for example in police recorded crime statistics they tend to combine violent crimes and sexual offenses into one category now this should be viewed with caution when you know doing your analysis because it tends to apply quite an overly holistic definition by conceptualising you know two pretty indifferent crimes but into one category so what effect is that going to have on your results especially if you were just interested in one or the other and the last kind of challenge that I'd like to address is just the impacts of seasonality for example how has COVID-19 affected police recorded crime statistics you know over the pandemic uh government put in restrictions they were forced to go into lockdown and there was new rules right and due to this increased government restriction there was reductions in certain types of crime for example there was a reduction in burglary as more people were forced to work from home therefore reducing the opportunity for these crimes to happen so yeah it's not entirely accurate to hold year-to-year comparisons because comparing trends from 2021 going to be innately different to trends in 2018 so there just a few of the main challenges but I realised I've been speaking for a little while so I'm going to give you the opportunity to see if you can think of any more head back to Mentimeter if you'd like and yeah share your opinion on what you think the main challenges of mapping crime data might be we'll come back to this in a minute or so so we've got a few responses coming through we have no data which I assume means that there is just some data that's not provided is that kind of link back to the figure of crime and that you know there is a the actual number of crimes recorded and the number reported are very different so we're missing a whole lot of information there another point that kind of links to this whole no-data thing is the way certain demographics of the population feel affected by having to call the police in fact there was a study by Graber and Stern which I think I've also left in the references and they highlighted that to call the police is a privilege of being white and you know police legitimacy can also affect the willingness to call the police this also means this also kind of leads on to the fact that a lot of crime data doesn't include demographic variables so we don't really know much about age or gender or race or religion or anything these crime data statistics provided by the police tend to just tell you about that crime type and where it was recorded there are obviously solutions to go about this by combining police data with other data sets like the census which we also do in the code demonstration but yeah something to think about dealing with sensitive data that's very true I guess this is kind of like back to the whole conversation of qualitative versus quantitative methods because the use of quantitative methods can be seen as pretty you know insensitive whereas running qualitative analysis on let's say the crime survey for England and Wales that tends to provide a much more individualistic experience of crime whereas these quantitative studies and quantitative analysis definitely has a larger application of generalising results just checking the time looks like we're doing well the political situation can impact the way of creating crime maps and some areas might not figure out the right number of crime data yeah you would absolutely be right you know different areas it could be easier or harder to report these crimes a lot of these crimes you know then go unreported as it is but unrecorded so there is a lot of missing data when it comes to crime which is definitely one thing I've noticed on this mediometer it worries me that something technical would go wrong when you say something technical I suspect you mean in terms of your own coding and analysis and I would like to say that that's absolutely fine I believe that coding is it's about trial and error it's about getting things wrong and understanding then how to correct these mistakes and I think that is the best way to learn especially with programme languages I've made mistakes on live code demonstrations I've made mistakes in in coding before and it happens just the only way you can really learn from your mistakes do not worry about getting errors and warning messages because they're all they can all be resolved but yes thanks all for participating in that I see that we have a question in the Q&A so let me just answer that one first the question states is cylindrical projection the most common form of projection when it comes to say weather data yes I would say that the macata projection which is under the cylindrical family this this type of projection minimizes the distortion near the equator which makes it better for tracking weather systems at low altitudes at a latitude sorry so the closer you are to the equator on a macata projection the more accurate the distance representation is so I hope it answers that cylindrical would be best for the data and if I had to give an example I'd probably say the macata projection so yeah that's kind of rounded off this webinar there are no more questions in the Q&A but feel free to keep answering I'll be around till half past but in the meantime I'll just explain to you the material for Wednesday most sorry all the material can be found on the github link which I think Emma will post into the chat again for you everything will be under the March 2023 folder now if you've never used github before then have no fear they will demonstrate how to obtain the data at the start of the code demonstration but to kind of summarize there are three ways you could get the data one is to simply clone the repository into your own computer the second would just to be download the folder that's on github onto your own computer and the third way is to use the interactive binder links that are available this third option is probably the best one in terms of people who do not have RStudio or get installed yet it means that you can run the code demonstration on your browser without having to install any excess any extra software it obviously means that this will run a bit slower and if you're trying to follow along during the code demonstration it might be a little bit slower but that'll the binders will be available indefinitely on the github so you can always do this in your own time I've got a list of the references that were used for this slide slide decks will be posted I believe at the end of the second talk and I also add these to the github account yeah thank you for completing all of the polls and surveys and a huge thank you to Emma and Jill for facilitating this webinar and yes so thank you all I'll hang around for five minutes for any questions and if not thanks all for attending