Features

Features and options included with each method of analysis are breifly described below. This list is not exhaustive but the main features are highlighted.

Item Response Theory

  • Rasch, partial credit, and rating scale models
  • Joint maximum likelihood estimation
  • MLE, MAP, and EAP estimation of examinee ability
  • Missing data allowed and handled by ignoring it or scoring it as zero
  • Save item parameter estimates to database
  • Save person parameter estimates to database
  • Item fit and scale quality statistics
  • Item map graph

Item Response Theory Linking and Equating

  • Handles IRT linking for binary and polytomous items
  • Supported linking models include any combination of Rasch, 2PL, 3PL, PCM, RSM, GRM, or GPCM
  • Mean/mean, mean/sigma, Haebara, Stocking-Lord procedures
  • Fixed common item parameter estimation for Rasch, partial credit, and rating scale models
  • Robust z statistic for item parameter drift
  • Item parameter correlations
  • Save transformed person and item values to database
  • IRT true score equating using any combination of Rasch, 2PL, 3PL, PCM, RSM, GRM, or GPCM

Test Scaling

  • Sum score, average score, percentile ranks, Kelley regressed scores, and normalized scores
  • Linear transformations of scale scores
  • Save scale scores to database

Frequency Analysis

  • Frequency and proportion endorsing a response
  • Cummulative frequency and cummulative relative frequency

Descriptive Statistics

  • Minimum
  • First quartile
  • Median
  • Mean
  • Third quartile
  • Maximum
  • Standard deviation
  • Interquartile range

Item Analysis

  • Proportion endorsing each response option
  • Option standard deviation
  • Flexible scoring allows user to assign score value to each option
  • Partial credit and multiple correct answers allowed
  • Point-biserial correlation
  • Biserial correlation
  • Test score descriptive statistics (see list of statistics above)
  • Reliability methods include Guttman's lambda 2, Cronbach's alpha, Feldt Gilmer coefficient, Feldt-Brennan coefficient, and Raju's beta
  • For a given method of reliability, the reliability and standard error of measurement if item deleted is optionally provided
  • 95% confidence interval provided for Cronbach's alpha
  • Standard error of measurement
  • Conditional standard error of measurement at cut-score
  • Huynh's decision consistency and raw agreement indices and standard errors

DIF Analysis

  • Currently based on Mantel-Haenszel procedure
  • Effect size computation (ETS Delta or standardized mean difference)
  • ETS DIF classification
  • Nonparametric IRT option charateristic curves illustrate DIF for each item and the test characteristic curve

Pie Charts

  • Edit chart title and subtitle
  • Graph individual variables
  • Graph multiple variable in trellis plot (plot with variables arranged in rows and columns)
  • Graph multiple variables in individual plots
  • Add 3D-effects
  • Chart frequencies or percentages
  • Chart variable according to a grouping variable

Bar Charts

  • Edit chart title and subtitle
  • Graph individual variables
  • Graph multiple variable in trellis plot (plot with variables arranged in rows and columns)
  • Graph multiple variables in individual plots
  • Add 3D-effects
  • Graph frequencies or percentages
  • Graph variable according to a grouping variable
  • Horzontal or vertical orientation

Histograms

  • Edit chart title and subtitle
  • Graph individual variables
  • Graph multiple variable in trellis plot (plot with variables arranged in rows and columns)
  • Graph multiple variables in individual plots
  • Graph histogram by group using transparent effect
  • Overlay normal distribution or kernel density estimate

Kernel Density Estimation

  • Edit chart title and subtitle
  • Graph individual variables
  • Graph multiple variable in trellis plot (plot with variables arranged in rows and columns)
  • Graph multiple variables in individual plots
  • Produce estimates by group
  • Choice of kernel

Nonparametric Item Response Theory Characteristic Curve Estimation

  • Edit chart title and subtitle
  • Graph individual variables
  • Graph multiple variables in individual plots
  • Choice of kernel
  • Score scale may be true score or normal score
  • Plot all response options or expected item score