Educational statistics Using R - 1. Descriptive statistics 3) inverse item variable

 

now make variables for inverse items

 

It easy to do it

 

[Maximum value among response +1] - [actual response values]

 

for example, 

 

someone response item 1 as 2, in Likert scale(5)

 

change the value 2 to 4(6-2=4)

 

But.. How do I know which item is inversed?

 

there are three way to check

 

first, Check the GuideBook about the item.

 

item developer would write about it

 

second, Check correlation among items

 

this will show the item's effect is postive or negative comparing with other items

 

Let's see

 

I use 10 items 

 

the items measures selfesteem

   

to analyse correlation, use 'cor' function

 

cor(dataset[,column number:column number],use = 'complete.obs', method = 'pearson')

use = 'complete.obs' : delete all NULL

method = 'pearson' : using pearson correlation

 

 

the result is..

 

I found the 5 inverse items (2, 5, 6, 8, 9)

 

in this survey, use 4 scale

 

so change their value like this

 

use index, select column number and replace values

 

and then, make a variable

 

 

 

to be continued..

 

Thank you.