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)

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.

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.

Examples

# NOT RUN {
# 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)
# }