CTT (version 2.3.3)

score.transform: Function for transforming scores onto different scales

Description

The function transforms the score metric by setting new scales' mean, standard deviation, and normalizing the distribution.

Usage

score.transform(scores, mu.new = 0, sd.new = 1, normalize = FALSE)

Value

The function returns a list with two vectors: new.scores is the transformed score and p.scores is the percentile rank of every examinee. If normalize=TRUE than percentile scores are used to create a roughly normal distribution by applying an inverse cumulative normal distribution function to the p.scores.

Arguments

scores

Vector for examinee scores

mu.new

Desired mean of the scale

sd.new

Desired standard deviation of scales

normalize

If normailize=True, the score will be normalized applying the inverse of the cumulative distribution function of the normal distribution to the respondents percentile score.

Author

John T. Willse, Zhan Shu

Examples

# Example data provided with package
data(CTTdata)
data(CTTkey)

# Data scored to demonstrate function
scores <- score(CTTdata,CTTkey)$score # obtain the scores

# the targeted mean=3, standard deviation=1

score.transform(scores,3,1)

# the score should be transformed by normalized precentile
score.transform(scores,3,1,TRUE)