eq {lazy.tools}R Documentation

Observed Score Equating

Description

This performs the observed score equating of the test score 1 to the test score 2.

Usage

eq(score1, freq1, cdf1 = NULL, score2, freq2, cdf2 = NULL,
  lim1 = NULL, lim2 = NULL, smooth1 = 0, bandwid1 = 3,
  smooth2 = 0, bandwid2 = 3, method = 2, title = "", nolow = 0,
  round = 1, print = 1, plot = 1)

Arguments

score1

a vector consisting of the score of test1

freq1

a vector consisting of the frequency counts at score1

cdf1

a vector consisting of the cumulative frequencies at score1

score2

a vector consisting of the score of test2

freq2

a vector consisting of the frequency counts at score2

cdf2

a vector consisting of the cumulative frequencies at score2

lim1

min and max score of test1

lim2

min and max score of test2

smooth1

# of times to smooth cdf1

bandwid1

bandwidth for running average smooth of cdf1

smooth2

# of times to smooth cdf2

bandwid2

bandwidth for running average smooth of cdf2

method

= 1 to use linear equating
= 2 to use equi-percentile equating

title

title string

nolow

= 1 to avoid lowering scores

round

= 0 not to round the result to integer. (not yet available)

print

= 1 to print the result

plot

= 1 to plot the conversion table
= 2 to plot the cdf
= 3 to plot the smoothed cdf

Details

Equipercentile equating is essentially the same as qqplot.
Therefore, the following two codes produce similar results:
eq( score1=score1, freq1=freq1, score2=score2, freq2=freq2 )
qqplot( expand_freqdist( score1, freq1 ) , expand_freqdist( score2, freq2 ), type="l" )
Note that, since native qqplot cannot handle case weight, expand_freqdist is used to recover the raw data from frequency table.

Value

a list of the following:
ctable: the conversion table consisting of (score, score21, freq1)
mands: the summary stat of the converted score dist: (score21,freq1)
newfreq: the frequency distribution of the converted score (score21, freq21)
sdist1 and sdist2: input and smoothed score distributions
cntr: a list of control parameters used.

Examples


seed <- 1701
set.seed(seed)

scoredist1 <- gen_test_score( 500, 0,10, beta=c(2,4), plot=1 )
scoredist2 <- gen_test_score( 1000, 0,15, beta=c(4,2), plot=1 )
reseq <- eq( score1=scoredist1[,1], freq1=scoredist1[,2]
           , score2=scoredist2[,1], freq2=scoredist2[,2]
           , smooth1=3, smooth2=3, method=2, plot=3 )


[Package lazy.tools version 0.1.3 Index]