| poly2dich {mirt} | R Documentation |
Transforms a matrix of items into a new matrix where the select polytomous items have been converted into comparable dichotomous items with the same information.
poly2dich(data, which.items = 1:ncol(data), sep = "_cat.")
data |
an object of class |
which.items |
a vector indicating which items should be transformed into the dichotomous form. Default uses all input items |
sep |
character vector pattern to append to each item name in |
Returns an integer matrix
Phil Chalmers rphilip.chalmers@gmail.com
Chalmers, R., P. (2012). mirt: A Multidimensional Item Response Theory Package for the R Environment. Journal of Statistical Software, 48(6), 1-29. doi:10.18637/jss.v048.i06
## No test:
data(Science)
head(Science)
## Comfort Work Future Benefit
## 1 4 4 3 2
## 2 3 3 3 3
## 3 3 2 2 3
## 4 3 2 2 3
## 5 3 4 4 1
## 6 4 4 3 3
newScience <- poly2dich(Science)
head(newScience)
## Comfort_cat.1 Comfort_cat.2 Comfort_cat.3 Comfort_cat.4 Work_cat.1
## [1,] 0 0 0 1 0
## [2,] 0 0 1 0 0
## [3,] 0 0 1 0 0
## [4,] 0 0 1 0 0
## [5,] 0 0 1 0 0
## [6,] 0 0 0 1 0
## Work_cat.2 Work_cat.3 Work_cat.4 Future_cat.1 Future_cat.2 Future_cat.3
## [1,] 0 0 1 0 0 1
## [2,] 0 1 0 0 0 1
## [3,] 1 0 0 0 1 0
## [4,] 1 0 0 0 1 0
## [5,] 0 0 1 0 0 0
## [6,] 0 0 1 0 0 1
## Future_cat.4 Benefit_cat.1 Benefit_cat.2 Benefit_cat.3 Benefit_cat.4
## [1,] 0 0 1 0 0
## [2,] 0 0 0 1 0
## [3,] 0 0 0 1 0
## [4,] 0 0 0 1 0
## [5,] 1 1 0 0 0
## [6,] 0 0 0 1 0
newScience2 <- poly2dich(Science, which.items = 2)
head(newScience2)
## Comfort Work_cat.1 Work_cat.2 Work_cat.3 Work_cat.4 Future Benefit
## 1 4 0 0 0 1 3 2
## 2 3 0 0 1 0 3 3
## 3 3 0 1 0 0 2 3
## 4 3 0 1 0 0 2 3
## 5 3 0 0 0 1 4 1
## 6 4 0 0 0 1 3 3
## End(No test)