WEBVTT Kind: captions; language: en-us

NOTE
Treffsikkerhet: 85% (H?Y)

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In this video we will see how to evaluate variables in jimovie. Let us first load our data set. 

NOTE
Treffsikkerhet: 91% (H?Y)

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In order to evaluate the normality of individual variables we have to do three things. One was the 

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visual evaluation of graphs, the other was the evaluation of indices, and the third was the 

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statistical testing of the normality assumption. 

NOTE
Treffsikkerhet: 89% (H?Y)

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These are all done through the exploration descriptives panel, 

NOTE
Treffsikkerhet: 88% (H?Y)

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so we can choose which variables to do these for 

NOTE
Treffsikkerhet: 84% (H?Y)

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for example the matrices in the word fluency in kindergarten and word fluency in first grade, 

NOTE
Treffsikkerhet: 90% (H?Y)

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and the first thing we have to do whenever we have a variable you want to look at is the histogram. 

NOTE
Treffsikkerhet: 91% (H?Y)

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So here is the histogram for the matrices 

NOTE
Treffsikkerhet: 88% (H?Y)

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for word reading fluency in kindergarten where most kids can't read and the same in first grade. And 

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to compare these distributions to the normal distribution we use the quantile quantile plot, so I 

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check on QQ here and I get the quantile quantile plot for each of the variables. 

NOTE
Treffsikkerhet: 91% (H?Y)

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To get the indices that are associated with the asymmetry or symmetry of the distribution and the 

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proportion of values away from the mean I have to go and check on skewness and kurtosis in the 

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distribution checks of descriptives. 

NOTE
Treffsikkerhet: 79% (H?Y)

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And the statistical evaluation of normality is done using the Shapiro Wilk test. 

NOTE
Treffsikkerhet: 91% (H?Y)

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So the skewness of each of the variables is shown on this line 

NOTE
Treffsikkerhet: 87% (H?Y)

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and you can see that the first and third variable have low, very low positive skewness is negligible, 

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and the second one has high positive skewness, and the kurtosis is shown on this row here so the first 

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and third variable have very low negative kurtosis that we can safely ignore but the second one has

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high positive kurtosis that we cannot ignore. 

NOTE
Treffsikkerhet: 84% (H?Y)

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And consistent with that the Shapiro Wilk test produces a low p-value for the second variable which 

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indicates that it is very unlikely we would have gotten this kind of distribution by sampling from a 

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normally distributed population, whereas the p-values for the other two are quite high and no cause 

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of concern 

NOTE
Treffsikkerhet: 88% (H?Y)

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and that is all you have to do in order to produce the necessary information for evaluating the 

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normality assumption in Jimovie.