WEBVTT Kind: captions; language: en-us NOTE Treffsikkerhet: 89% (H?Y) 00:00:00.000 --> 00:00:06.300 In this video, we're going to talk about the distinction between dependent and independent 00:00:06.300 --> 00:00:13.500 variables. This is a very important distinction in research design, but is also very important in 00:00:13.500 --> 00:00:21.000 statistics in order to properly set up the analyses. So it is useful to understand what these terms 00:00:21.000 --> 00:00:28.000 actually mean. Let's go back to the fundamental of setting up a research question, which as we have 00:00:28.000 --> 00:00:30.150 said, always must concern a relationship NOTE Treffsikkerhet: 88% (H?Y) 00:00:30.150 --> 00:00:37.700 among variables. This means that in order to ask a question that can be answered by research. We 00:00:37.700 --> 00:00:46.100 have to narrow the question down and precisely define everything about measuring the variables that 00:00:46.100 --> 00:00:53.400 go into this question. So everything has to be cast in terms of variables, their measurement, the 00:00:53.400 --> 00:01:00.349 context, and the conditions under, which they are measured. In general we usually are NOTE Treffsikkerhet: 91% (H?Y) 00:01:00.349 --> 00:01:08.500 interested in what effects some Target. Some outcome. This target variable is therefore called a 00:01:08.500 --> 00:01:16.600 dependent variable because by design, by the nature of our question, we are interested in what it 00:01:16.600 --> 00:01:25.050 depends on or whether it depends on something. This leaves out the things that it might depend on 00:01:25.050 --> 00:01:30.449 and therefore all the other variables that are used essentially as predictors for it NOTE Treffsikkerhet: 91% (H?Y) 00:01:30.449 --> 00:01:38.400 are called independent variables. So this is just designed terminology. By calling a variable 00:01:38.400 --> 00:01:44.600 independent we're not really saying that it's independent of anything else. It's one more poor 00:01:44.600 --> 00:01:47.900 choice of words in statistical terminology. NOTE Treffsikkerhet: 91% (H?Y) 00:01:47.900 --> 00:01:55.400 Independent variable means we use it to predict another variable. Dependent variable means this is 00:01:55.400 --> 00:02:01.900 our outcome of interest and the variable that we are assuming or asking whether it is affected by 00:02:01.900 --> 00:02:11.700 others. Let's go through some examples to understand this better. So, one silly example, is to 00:02:11.700 --> 00:02:18.300 ask the question, does coffee help studying, but this is a very vaguely phrase question. NOTE Treffsikkerhet: 83% (H?Y) 00:02:18.300 --> 00:02:25.000 In fact, it's not possible to answer this question because it's not well specified. In order to be 00:02:25.000 --> 00:02:30.200 able to answer it we have to define specific variables that we can then measure in. There are many 00:02:30.200 --> 00:02:35.500 many options will not going to go through many of them, but we'll just see, two completely different 00:02:35.500 --> 00:02:44.900 examples. One possibility is to define one variable as the number of espresso cups per day and 00:02:44.900 --> 00:02:48.050 another variable as the number of hours spent reading per day. NOTE Treffsikkerhet: 72% (MEDIUM) 00:02:48.050 --> 00:02:48.900 NOTE Treffsikkerhet: 89% (H?Y) 00:02:48.900 --> 00:02:56.500 So essentially this is like asking does how many espresso a day, does how many espresso we 00:02:56.500 --> 00:03:03.500 drink in a day affect how many hours we study in a day? That's what we're asking. NOTE Treffsikkerhet: 91% (H?Y) 00:03:03.500 --> 00:03:09.200 And if we put it this way, then this means that NOTE Treffsikkerhet: 91% (H?Y) 00:03:09.200 --> 00:03:15.200 the number of espresso cups would be our independent variable and the number of hours spent reading 00:03:15.200 --> 00:03:17.650 would be our dependent variable. NOTE Treffsikkerhet: 88% (H?Y) 00:03:17.650 --> 00:03:25.300 Now, you might object that, this isn't what you really interested in when you are asking, whether 00:03:25.300 --> 00:03:30.400 coffee helps. But that just means that you're going to have to define your variables differently. 00:03:30.400 --> 00:03:37.200 And before we go on to another definition. Let me remind you that this is still way too vague. 00:03:37.200 --> 00:03:44.200 We have to specify whom we ask what they do, what else they might be doing if they drink any other 00:03:44.200 --> 00:03:47.750 things. When we measure these, how often NOTE Treffsikkerhet: 91% (H?Y) 00:03:47.750 --> 00:03:52.600 exactly what the observations or questions are and so on. NOTE Treffsikkerhet: 91% (H?Y) 00:03:52.600 --> 00:03:58.900 So this is just the first step in defining variables so that they can be designated as dependent or 00:03:58.900 --> 00:04:07.550 independent. A different approach to the same general question might be to define the variable as a 00:04:07.550 --> 00:04:15.399 the property of drinking coffee versus drinking soft drinks, like Coke, or bruse or what else some 00:04:15.399 --> 00:04:17.200 people might be drinking. NOTE Treffsikkerhet: 91% (H?Y) 00:04:17.200 --> 00:04:25.000 And another variable as the average grade in semester courses. So this might be more interesting for 00:04:25.000 --> 00:04:33.000 some. These are very different variables. The first variable is actually a grouping variable. It's a 00:04:33.000 --> 00:04:38.900 person who drink coffee versus persons, who don't drink coffee, but drink is another category of 00:04:38.900 --> 00:04:44.299 drinks and that would be our independent variable, the group, NOTE Treffsikkerhet: 85% (H?Y) 00:04:44.299 --> 00:04:51.500 and the dependent variable would be a grade. So asking if there are differences in grades between 00:04:51.500 --> 00:04:59.000 these two groups of people and we still need to define a whole bunch of other details before you can 00:04:59.000 --> 00:05:05.200 actually produce an answer to this question by running the measurements in the analyses. So you see 00:05:05.200 --> 00:05:06.300 that NOTE Treffsikkerhet: 87% (H?Y) 00:05:06.300 --> 00:05:12.800 the general questions does coffee help studying is very far from being answerable. The many 00:05:12.800 --> 00:05:19.450 different ways to make it specific enough. And in the process, we have to define specific variables 00:05:19.450 --> 00:05:25.100 and one of those variables is going to be our target and that's our dependent variable that we want 00:05:25.100 --> 00:05:31.000 to study if it's affected and the other variable, the predictor, is called the independent one. NOTE Treffsikkerhet: 91% (H?Y) 00:05:31.000 --> 00:05:34.200 Let's look at some more examples. NOTE Treffsikkerhet: 91% (H?Y) 00:05:35.000 --> 00:05:44.700 So, one question might be does music affect aggression. This is very vague. Of course, we candDefine 00:05:44.700 --> 00:05:50.400 it in many ways, for different groups and for different purposes. So, for this illustration, I'm 00:05:50.400 --> 00:05:58.400 just keeping it very simple. And let's say that one way to define it would be by groups such that 00:05:58.400 --> 00:06:04.400 people in one group are asked to listen to Kpop all day and people in other group, listen to 00:06:04.400 --> 00:06:05.800 NRK Jazz all day. NOTE Treffsikkerhet: 87% (H?Y) 00:06:05.800 --> 00:06:12.550 And other people are asked to listen to death metal music all day, and they do that for some time, 00:06:12.550 --> 00:06:19.000 which is part of what needs to be defined. And then we ask them to fill out an aggression 00:06:19.000 --> 00:06:20.350 questionnaire. NOTE Treffsikkerhet: 90% (H?Y) 00:06:20.350 --> 00:06:27.000 And in this case, the group which kind of music, they are asked to listen to the group would be our 00:06:27.000 --> 00:06:32.500 independent variable. And the score on this aggression questionnaire would be our dependent 00:06:32.500 --> 00:06:38.600 variable. And, of course, we would have to define a whole bunch of other things. NOTE Treffsikkerhet: 91% (H?Y) 00:06:38.600 --> 00:06:46.900 Another completely different conceptualization of this question would be to note, how long each 00:06:46.900 --> 00:06:54.000 person listens to music per day and we have to define for how many days you 00:06:54.000 --> 00:07:01.100 want to do this for one day for a week or how long or every Monday for a year, whatever we decide. 00:07:01.100 --> 00:07:08.150 And we also at some point need to define some measure of aggression. So NOTE Treffsikkerhet: 73% (MEDIUM) 00:07:08.150 --> 00:07:16.200 another variable might be an aggression assessment checklist in which an observer checks some 00:07:16.200 --> 00:07:22.800 items. And, for example, this can be used with special populations or with children and so on, and 00:07:22.800 --> 00:07:30.100 we need to define the all the conditions for it. In this case number of our listening to music 00:07:30.100 --> 00:07:36.700 would be our independent variable and the score on the aggression checklist will be our dependent 00:07:36.700 --> 00:07:38.300 variable. NOTE Treffsikkerhet: 91% (H?Y) 00:07:38.900 --> 00:07:42.100 Different examples. NOTE Treffsikkerhet: 80% (H?Y) 00:07:43.000 --> 00:07:52.200 A very interesting example in our context is does intervention for something work; for reading for 00:07:52.200 --> 00:08:00.300 emotional difficulties, for behavior problems, for language, for whatever, for X does intervention for 00:08:00.300 --> 00:08:08.700 something work. We need to define variables. One possibility is to have an intervention group and a 00:08:08.700 --> 00:08:13.650 control group. So the intervention group receives intervention the control group NOTE Treffsikkerhet: 91% (H?Y) 00:08:13.650 --> 00:08:24.300 One way to define these is to have an intervention and a control group. The intervention group 00:08:24.300 --> 00:08:30.000 receives the intervention and the control group is engaged in something else. NOTE Treffsikkerhet: 80% (H?Y) 00:08:30.000 --> 00:08:39.299 And after the intervention, after some time of doing this. Then both groups are assessed with a test 00:08:39.299 --> 00:08:45.600 and we measure their performance. So, here the independent variable is group in the dependent 00:08:45.600 --> 00:08:54.600 variable is the score with the performance on this assessment test. That is a valid instrument for 00:08:54.600 --> 00:09:00.350 measuring X, whatever it is. We want to improve with the NOTE Treffsikkerhet: 79% (H?Y) 00:09:00.350 --> 00:09:05.750 And, of course, there's lots of other details that need to be defined in our research design. 00:09:05.750 --> 00:09:14.400 Another approach to this question, is to define a different variable, the variable of time. So, that 00:09:14.400 --> 00:09:20.650 time would have the value before intervention and the value after intervention. NOTE Treffsikkerhet: 91% (H?Y) 00:09:20.650 --> 00:09:29.400 And another possibility for the outcome here would be an assessment checklist. So for some things, 00:09:29.400 --> 00:09:38.650 it may be preferable or only possible to assess the x that we're trying to improve by observation, 00:09:38.650 --> 00:09:46.200 in which case you have to use the checklist. So we define our outcome accordingly and this means 00:09:46.200 --> 00:09:51.250 that we basically assess the participants twice. NOTE Treffsikkerhet: 79% (H?Y) 00:09:51.250 --> 00:09:59.550 Once before the intervention and once after the intervention. So the independent variable is time 00:09:59.550 --> 00:10:06.400 and the dependent variable is the score on this assessment checklist. NOTE Treffsikkerhet: 88% (H?Y) 00:10:06.400 --> 00:10:14.700 So you see two different design approaches. One is to have an independent variable of group. The 00:10:14.700 --> 00:10:20.900 other is to have the independent variable of time. And in real research want to do this properly. We 00:10:20.900 --> 00:10:26.700 actually use both independent variables. So we have two groups and we says both groups before, and 00:10:26.700 --> 00:10:32.500 after, for reasons that you're going to learn in the research design part of the course. NOTE Treffsikkerhet: 86% (H?Y) 00:10:32.800 --> 00:10:42.100 And some final examples. We can ask for, for example, are girls better than boys in math? NOTE Treffsikkerhet: 90% (H?Y) 00:10:42.600 --> 00:10:49.300 Of course, this needs to be specified like in what age, what math are we talking about and so on. 00:10:49.300 --> 00:10:55.500 But anyway, we can define the variable of sex. This is obviously our independent variable and the 00:10:55.500 --> 00:11:01.750 dependent variable, could be performance on some math assessment test. For example, the state test, 00:11:01.750 --> 00:11:06.950 the national assessment on math performance in a given age. NOTE Treffsikkerhet: 91% (H?Y) 00:11:06.950 --> 00:11:17.100 Or we can ask something like, are children with dyslexia better in art things. So, here we would 00:11:17.100 --> 00:11:24.300 have a group variable distinguishing children diagnosed with dyslexia from children, typically 00:11:24.300 --> 00:11:26.849 developing in their reading skills. NOTE Treffsikkerhet: 86% (H?Y) 00:11:26.849 --> 00:11:33.100 And the two groups would probably have to be matched in some other things. So they should be as 00:11:33.100 --> 00:11:40.450 similar as possible except for the dyslexia diagnosis. And that would be our independent variable, 00:11:40.450 --> 00:11:46.950 the group or the diagnostic category. That's our independent variable and the dependent variable 00:11:46.950 --> 00:11:53.100 would be the score on some instrument for assessing artistic skills. NOTE Treffsikkerhet: 91% (H?Y) 00:11:54.300 --> 00:11:57.750 And one final example. NOTE Treffsikkerhet: 91% (H?Y) 00:11:57.750 --> 00:12:08.000 We could ask do minority language speakers have for Norwegian vocabulary. So, in that case, again, 00:12:08.000 --> 00:12:15.100 our independent variable is a grouping variables. It's a group. We would have children with the 00:12:15.100 --> 00:12:20.600 minority home language, in one group and otherwise comparable children with the majority home 00:12:20.600 --> 00:12:26.100 language. So they would have to be matched in other things, you know, from the same neighborhoods 00:12:26.100 --> 00:12:28.300 and circumstances and so on. NOTE Treffsikkerhet: 86% (H?Y) 00:12:28.300 --> 00:12:35.700 That would be our independent variable and our dependent variable would be some score on 00:12:35.700 --> 00:12:39.400 appropriate vocabulary test for the age. NOTE Treffsikkerhet: 91% (H?Y) 00:12:39.400 --> 00:12:47.500 So I hope this concept is now clear and please go through more examples, yourselves. You connect the 00:12:47.500 --> 00:12:53.300 nature of a research question to the concept of what is the dependent and what is the independent 00:12:53.300 --> 00:12:54.900 variable.