# dprime_test: Test of simple hypothesis with the common d-prime In sensR: Thurstonian Models for Sensory Discrimination

## Description

This function tests the hypothesis that the common d-prime is equal to or greater/less than a certain value, e.g. zero in a Wald or likelihood root test.

## Usage

 ```1 2 3 4``` ```dprime_test(correct, total, protocol, conf.level = 0.95, dprime0 = 0, statistic = c("likelihood", "Wald"), alternative = c("difference", "similarity", "two.sided", "less", "greater"), estim = c("ML", "weighted.avg")) ```

## Arguments

 `correct` a numeric vector of the number of correct answers; one element for each test. `total` a numeric vector of the total number of trials; one element for each test. `protocol` a character vector or factor naming the protocol used; one element for each test. Currently the following protocols are supported: `"triangle", "duotrio", "threeAFC", "twoAFC", "tetrad"`. `conf.level` the confidence level for the confidence interval of the estimated common d-prime. `dprime0` Value of d-prime under the Null hypothesis. Non-negative numeric scalar. `statistic` the test statistic for computing the confidence interval as well as p-value. `alternative` the direction of the hypothesis test. `"difference"` and `"similarity"` are just alternative ways of specifying `"greater"` and `"less"` respectively. `estim` The estimation method for the common d-prime.

## Details

The vectors `correct`, `total` and `protocol` have to be of the same length.

The function has a print method.

## Value

an object of class `"dprime_test"` with the following elements

 `p.value` the p-value for the 'any-differences' test. `alternative` character naming the direction of the hypothesis test.
 `statistic` the name of the test statistic. `data` the data table produced by `dprime_table`. `conf.level` confidence level for the common d-prime. `conf.int` the confidence interval for the common d-prime. `estim` the estimation method for the common d-prime. `conf.method` the statistical method/test statistic used to compute the confidence interval for the common d-prime.

## Author(s)

Rune Haubo B Christensen

`dprime_compare`, `dprime_table`, `posthoc.dprime_compare`.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12``` ```n <- rep(40, 4) x <- c(25, 25, 30, 35) protocol <- c("triangle", "duotrio", "threeAFC", "twoAFC") ## Look at the data table with d-primes etc.: dprime_table(x, n, protocol) ## Test of common d': dprime_test(x, n, protocol) ## Another setting: dprime_test(x, n, protocol, dprime0=2, statistic="Wald", alternative="less", estim="weighted.avg") ```