 So, concepts that we kind of explore through a causal loop diagram or of course, causand effect that is the way it is called causal loop diagram, we try to understand the feedback loops. See if at the end of it if your causal loop diagram is just a linear thing a of x b, b of x c, c of x d, that is not a loop there is just a linear regression model there is no feedback nothing is happening here. The entire thing which makes it difficult is when feedback starts to kick in it makes the system complex and key causal links that we are interested in are those inside those feedback loops. And then positive feedback loop even number of negative signs it will have an amplifying effect it will have cause reinforcement it will cause growth or a rapid decline essentially all these systems are becomes unstable without something to balance or something to goal seek or negative feedback loop are balancing, stabilizing stable equilibrium often good that is what it all the terms positive and negative here it can be a misnomer positive it just goes with the number of direction of movement and things like that. But what we are actually looking for is what are things that is causing the system to balance to stabilize stable equilibrium. And this feedback system and everything even many of our day to day lives are even simple electromechanical system all are based on feedback there is AC in this room is based on feedback imagine if there is no nothing to balance it is going to get super cold. So, there has inherently there will be a balance even if the system even if there is some failure point within the sensors there will be other natural balancing factors like how much what are the cooling agent we have in the system or what is the capacity of it how much it can actually cool etcetera. So, those are the things which is going to limit the temperature in the room. So, there are various factors that can cause the system to not go grow beyond a point. So, all those are good or when we drive a car or drive a bike we continuously take feedback it is not like when you left the hostel and even if you know which path to take you have to consider instantaneous feedbacks from the trucks and bus which comes other cyclists friends etcetera etcetera as you come here you cannot just expect to do your thing without taking any feedback at all. So, those are completely it is always inherent in the system. We are trying to make it explicit in very mechanical systems electrical systems it becomes more controllable and easy. Once you move into the social systems it becomes little more difficult like driving a car because lot of feedback you have to be really alert people will give you unwanted feedbacks everything is there. So, then it becomes difficult to model it very easy to model the traffic when it is smooth flowing. Modeling congestion is very difficult that means, there is continuous feedback happening people have to you know they have to still ride. But eventually people reach their places it is not that nothing happens people go home people go to work people commute things life moves on by taking continuous feedbacks. And delays also occurs in the feedback loops from everything, but only thing we have to be on your time units matter just because you are doing causal loop on systems level at least pay attention to the time units. Units matter here time units matter. So, usually if the we take some time units for the causal loop diagram say the time units can be say in weeks or months or years and if everything is corresponding to that yearly thing then we do not put any delay mark. If something is causing additional delays beyond our regular time units that we are taking that is when we use the delay mark. So, and everything takes a delay mark or tea breaks are long source of long delays in doing assignment studying for example, but that is how it is. So, I am sure as students or masters PhDs can delay click then faculty goes for tea it takes long time for them to come back or waited they do for meeting them. So, there is lot of delays. Let us look at some guidelines for the CLDs. All links should have unambiguous polarities ambiguous polarities can indicate presence of other pathways meaning you can have only plus or minus you cannot write it depends choose and say plus or minus answer cannot say it depends on lot of things that do not work. If it all it depends then you have to uncover what it depends on depends then elaborate the statement do not just stop there that is what we mean by alternate pathways there is something else that is affecting list all those things the model will look bigger which is fine. There is no this thing for brevity point. So, you just go ahead and list what are alternate pathways are there. The second point is proper variable names. Variable names prefer to be nouns or noun phrases actions are captured by the causer link themselves. So, you do not need to write the action or verbs as a variable. Variable should be nouns or noun phrases. Choose variable names whose normal sense of direction is positive. You do not need to say this causes this or whatever criticism increases unhappiness when say criticism decreases happiness. So, a normal sense can be in the positive or whatever cause increases losses say cause decreases profit that could be the variable names normal sense can be the positive direction. So, it is easier for us to visualize certain things same thing a normal sense of direction is positive for the variables. Let us take these three things and do some examples for that it is called link and the duty. Standard model for economics is price and revenue. Price affecting revenue depends sometimes on prices large of course, you know it is it should increase my revenue. But that is not always so because revenues may is actually calculated not on one product but usually on many sales of many products and if price is too high then people may stop buying things. So, there is a bigger narration there is a just relating price to revenue. So, on left side I will try to write the incorrect one on right side I will try to do the correct one. So, do that you can identify alternate pathways. So, as price increases we expect revenue to increase, but as price increases sales can fall down it is from basic economic theory, but revenue is always just quantity sold into the price of product. So, both direction is the same revenue is nothing but sales into price. So, we just use the same relationship that we study in other economics course revenue is product of sales and price, but as price increases sales can come down which had caused some ambiguity here saying whether when price alone if you keep it then we do not get the full picture. So, that is what we mean by ambiguous thing. So, you do not do this or you do not say like this you do not do these things these are all incorrect you do not do a plus slash minus. So, let us look at variable names here the point was the variable name should be known on phrases and we should avoid the action for the action is already captured in the arrows that is what we have already have. So, again whatever you write on left side is the incorrect ones. So, we do not write cost, price increases to price increases and that is not correct the correct one would be cost increases in general price increases. Again these are all we are just focusing on one small link do not be too critical on those two variables. We will just take it by that or increasing prices of goods, results in increasing sales of goods, sales of goods demand for wages or salaries. So, this is how the typical narration which we need talk to clients and others or study a system this is what the narration will come out in price order GST comes GST goes whatever does not matter new taxation comes the price is increasing so there is a pressure to increase your wages and salaries. But to capture it we can just simply write it as price of goods increases demand for wages. So, the action is already captured by the link. So, when we read this link itself we read it the way as cost has cost increases we are looking at the plus sign as cost increases the price of goods also increase or the price of goods increases it increases the demand for wages. So, this plus sign indicates that. So, I was here increasing price of goods as that increases it increases the increasing demand for wages it is a very complicated conclusion narration increasing decreasing and all those things we leave it to the S.A. link and the plus sign. Where are some increases, decreases, increasing, decreasing all those you leave it to the symbols. For the loop you need to look at the bigger system fully this is a simple example. Higher inventory we can then give a negative link example also results in low delivery delay. So, what you are saying is if I am well stocked I have a lot of inventory I can deliver the product to you in very short time that is what people want. So, that is what I want to say and they will say I have higher inventory which results in lower delivery delay. But to capture it correctly we say inventory decreases delivery delay. So, here when we read it its inventory increases expect my delivery delay to come down because I have ready stock available to meet whatever demand that can come in future. So, this is a correct way to write it. So, right side is all the correct ways this is not the correct ways. So, higher or low itself. Allow the action to describe by the links. So, at that let me just say that and stop it normal direction is positive. Let me give the same example again not to itself. Don't say cost increases losses or criticism increases unhappiness. It is just these are just guidelines. It is a rather we can try to say cost decreases profit or revenue whatever it is imagine. So, these are criticism decreases your happiness this is some again as I told on this side is incorrect one and these sides are correct ways. This is just common practices. So, that when the outcomes when you start looking at it when you match you can easily compare right. We typically we want higher the better kind of thing. So, we want to from the ground from the start itself use variable names with normal senses in the positive direction. So, that when we actually analyze it later it brings a narration. Otherwise, it looks like there is some double negative thing happening and it is all what we want to do. So, I will just stop here. So, tomorrow we will again meet 11.30. So, tomorrow we may go little beyond class hours may be till 12.45 or 12.50 because we are going to do some examples it depends on how long you take to complete examples. So, plan to be here at least till 1 o'clock. Thanks.