# utils: Utility functions In Rirt: Data Analysis and Parameter Estimation Using Item Response Theory

## Description

`rmse` computes the root mean squared error (RMSE) of two numeric vectors/matrices

`freq` computes the frequency counts of a numeric or character vector

`cronbach_alpha` computes the Cronbach's alpha internal consistency reliability index

`spearman_brown` predicts the reliability when the current test is extended to n times longer

`spearman_brown_reverse` computes how many times the current test length needs to be extended in order to reach targeted reliability

`quadratic kappa` computes the quadratic weighted kappa of two numeric vectors

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11``` ```rmse(x1, x2) freq(x, vals = NULL, decimal = NULL) cronbach_alpha(u) spearman_brown(rho, n_len) spearman_brown_reverse(rho, target_rho) quadratic_kappa(x1, x2) ```

## Arguments

 `x1` a numeric vector or matrix `x2` a numeric vector or matrix `x` a numeric or character vector `vals` valid values, `NULL` to include all values `decimal` round results to n-th decimal places `u` oberved responses, 2d matrix `rho` the reliability of the current test `n_len` extend the test to n times longer `target_rho` the targeted reliability

## Value

`freq` returns the frequency counts and percentages in a data.frame

## Examples

 ```1 2 3 4 5 6``` ```rmse(rnorm(10), rnorm(10)) freq(round(runif(100, 1, 5))) cronbach_alpha(model_3pl_gendata(1000, 20)\$u) spearman_brown(.70, 2) spearman_brown_reverse(.70, .85) quadratic_kappa(round(runif(100, 1, 5)), round(runif(100, 1, 5))) ```

Rirt documentation built on Oct. 30, 2019, 12:13 p.m.