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
- 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 Equating
- Handles IRT equating for binary items
- Rasch, 2PL, and 3PL models supported
- 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
Test Scaling
- Sum 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
Confirmatory Factor Analysis
- Estimation of parameters for unidimensional congeneric, tau-equivalent, and parallel models
- Multiple fit statistics
- CFA based reliability estimate
- It's just the beginning. More CFA features will be added soon.
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