Name | Modified | Size | Downloads / Week |
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README.rtf | 2020-04-26 | 2.8 kB | |
rsdif.R | 2020-04-26 | 8.7 kB | |
rsdif_IVI_28.RData | 2020-04-26 | 99.7 kB | |
Totals: 3 Items | 111.2 kB | 0 |
{\rtf1\ansi\ansicpg1252\cocoartf1671\cocoasubrtf600 {\fonttbl\f0\fswiss\fcharset0 Helvetica;} {\colortbl;\red255\green255\blue255;} {\*\expandedcolortbl;;} \margl1440\margr1440\vieww10800\viewh8400\viewkind0 \pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\pardirnatural\partightenfactor0 \f0\fs24 \cf0 \ CODE IMPLEMENTING RATING SCALE DIF:\ \ \'91rsdif.R\'92 implements rating scale DIF and rating scale DPF. \ \ Required inputs to \'91rsdif.R\'92:\ \'91items\'92 = a numeric vector of item measures with no NA.\ \'91persons\'92 = a numeric vector of person measures with no NA.\ \'91thresholds\'92 = a numeric vector of ordered rating category thresholds with no NA.\ \ Optional inputs to \'91rsdif.R\'92:\ \'91dpf\'92 = logical for calculating rating scale DPF instead of rating scale DIF (the default). \ Default is FALSE.\ \'91normpdf\'92 = logical for using a standard normal distribution instead of the logistic distribution (the\ default). Default is FALSE.\ \ Output of \'91rsdif.R\'92 is a list whose elements are:\ \'91DIF_up\'92 = a numeric vector of rating scale DIF criteria for each item in the upwards direction.\ \'91DIF_down\'92 = a numeric vector of rating scale DIF criteria for each item in the downwards direction.\ \'91DIF_average\'92 = overall average of all \'91DIF_up\'92 and \'91DIF_down\'92 criteria.\ \ Output of \'91rsdif.R\'92 is changed to \'91DPF_up\'92, \'91DPF_down\'92 and \'91DPF_average\'92 if \'91dpf\'92 = TRUE\ \ \ EXAMPLE OF USE:\ \ # Generate a random set of item measures, person measures and ordered thresholds:\ IM = runif(100, -2, 2)\ PM = runif(500, -2, 2)\ TH = sort(runif(5, -2, 2))\ \ # Calculate rating scale DIF\ A = rsdif(IM, PM, TH)\ \ # Results are in:\ A$DIF_up\ A$DIF_down\ A$DIF_average\ \ \ RESULTS OF MSD AND RSDIF ANALYSIS OF IVI-28:\ \ \'91rsdif_IVI_28.RData\'92 contains a list called \'91RSDIF_results\'92 whose elements are:\ \'91MSD_parameters_IVI_28\'92 = a list of parameters estimated by the Method of Successive \ Dichotomizations, or MSD, using the R package \'91msd\'92. Parameters\ include item measures, person measures and rating category \ thresholds used as inputs to the \'91rsdif.R\'92 program\ \'91DIF_IVI_28\'92 = a list of estimated rating scale DIF criteria in both DIF directions for every item, as\ well as the overall DIF average (see output of \'91rsdif.R\'92).\ \'91DPF_IVI_28\'92 = a list of estimated rating scale DPF criteria in both DPF directions for every person,\ as well as the overall DPF average.\ }