 All right, so we're back here with our awesome non-linear process of science visual and we're going to now focus in on this idea of testing Ideas we're testing Observations we're testing concepts. We're testing hypotheses if you roll over the testing ideas Circle you'll see that it does begin with a hypothesis that a Hypothesis and I say it begins with hypothesis you are seeing Observations you're you're seeing things around you and you develop this this idea That then relates to collecting data. We've talked about the hypothesis a lot the thing that I want to talk further about in this section is a little bit more of the nitty-gritty on Designing the experiment. So how do we actually test that hypothesis? I? Wonder if you can hear my neighbor Mowing their lawn right there. I Bet you can't hear it Well, no, there's a weed eater happening out there that You hear that I'm gonna try really hard to ignore it. Okay Part of we've identified a hypothesis and part of the the next thing to do is to set up an Experiment and when we do an experiment we need to Identify the variables that we'll be dealing with in that experiment I'm gonna write them all down first so that you have them and then we're gonna talk about each one We have the independent the independent variable which suggests the presence of a dependent variable and We have a controlled or I'm gonna say it standardized Variable I tend to use the word standardized variable But when I look around Most places are calling it a controlled variable. So I feel like Controlled might be a little more intuitive, but I definitely if you hear me saying standardized variable That's what I'm referring to and then the last one. I think is also It's an important one and Its name is Gonna tell you what it is. It's a confounding Variable Okay, so we have four types of variables and I've listed them I Think in an order that's gonna help us Remember what they are at the top of the list is the independent Variable and I'm gonna tell you right now in any experiment You want one you want one Independent variable and I'm gonna tell you what it is. This is the thing you change in your experiment so if you're looking at Survival rates for What are those little sea monkeys brine shrimp in different amounts of Sodium concentration Did you follow what I just said? Your question might be Ken's brine shrimp. What's their favorite concentration of sodium in Water for their survival The thing you're changing in all in your experiment the thing that you're looking at is sodium levels So in one group, you're gonna have No sodium and the next one you're gonna have a little bit And then you're gonna have a little bit more and then you're gonna have a lot of sodium and you've got this range of Changes to one variable sodium concentration The independent variable there's only one I think that's probably the most helpful piece of an independent variable to remember when you're trying to remember these definitions No, the independent one is alone. There's only one of them the dependent variable Glory days you can have as many as you want And not only can you have as many as you want? That that's because That's what you're measuring the dependent variable is what you measure Independent variable just one and it's the thing you're changing dependent variable How many measurements do you want to take? How many things do you want to look at when I change the salt concentration of the environments for these poor little brine shrimp in my experiment What are going to be the things that I want to know? What what am I measuring? Well, I got a sad story to tell you probably should measure the number of brine shrimp that stay alive So the number that die and the number that stay alive that would be a good dependent variable What if you measured birth Like can they reproduce in that environment? Which environment are they more likely to reproduce in? That might be another dependent variable What else maybe you could measure something about their activity like do they how much do they move? Maybe there's a way to quantify How much they move or even maybe there's a way to quantify how much food they're taking in or Mmm, how much carbon dioxide they are producing there are things that we can Measure that will help us understand the impact of that thing that we change because the dependent variable is We can have as many of them as we want You only need one you your question might be really simple that you want to know how it impacts Survival and then you have one thing you're gonna count the dead guys and that's gonna be The dependent variable that you have You're controlled again. The name now tells you Independent variable and dependent variable are easy to get mixed up Just remember the independent variable is the guy on top the first one on the list and there's only one Controlled variables are all the things that you need to keep the same in Your experiment everywhere. So let's just put that down there the all Things you Keep the same All the things that you're gonna hold constant those are your controlled and standardized variables and you The best experiments have the best controls You're controlling everything You can imagine that Maybe our brain shrimp experiment. Yes, let's do this We're changing the salt concentration in our water. We're changing the salinity of the water but what we're gonna control is The amount of food each group gets in each different treatment pile Their food is all the same. They're all gonna get the same amount of food We're gonna control. Let's control the pH of the environment Let's make sure that the pH of their little homes are the same for all the groups Let's control that let's control the number of critters that we start with so we're gonna have and Brain shrimp this might be difficult, but maybe we should try to control the some qualities about Brain shrimp, I don't think this would be something you'd control in actual brain shrimp But if you're doing experimentation on humans, you definitely want to have there's lots of Qualities of a human age of a human Biological anatomical sex of a human Their chromosomes that they might have any conditions that they might have how much they exercise what they ate that morning These are all qualities that can impact, right? Like they're confound or their their variables that could impact your outcomes if you don't control them You want to have as many of them controlled as you possibly can and one of our observations Somewhere in this lecture that is growing longer and longer by the minute Somewhere in here we talked about The fact that it's really hard impossible To control for everything so you do the best that you can and you can guarantee that the things that you don't control will be Criticized in the sign like yes I didn't control for that thing and this is why I decided not to control for it or this is why it was impossible To control for that thing So as many things as we can control we want to the last one Once a variable is determined that it can't be controlled It becomes a confounding variable Uncontrollable it's super interesting Doing science on humans You end up with this giant pile of confounding variables I've been messing around with Educational research like doing collecting data on my students and Then trying to analyze the the results of the data and draw conclusions about what kinds of teaching strategies are most effective for students I Mean the number of confounding variables in this is profound like How much experience do students have coming into a course? Have they ever had a biology course before? Do they like watching videos? Do they like? Communicating with their teachers. I mean there's just a million things that are confounding when you start looking at research on humans But you can see how the more confounding variables you have the less Reliable Your results are going to be It's why it's so good to have a community of humans looking a community of experts looking at the research looking at the results looking at the design and Ensuring that as many of those confounding variables are eliminated as possible Okay, we've done variable land. Oh my goodness. Are we having fun yet? Please say yes Next up we're gonna talk about different kinds of controls