# findcr: Find the critical value of a one-tailed binomial test In sensR: Thurstonian Models for Sensory Discrimination

## Description

Finds the critical value in a one-tailed binomial test

## Usage

 ```1 2``` ```findcr(sample.size, alpha = .05, p0 = .5, pd0 = 0, test = c("difference", "similarity")) ```

## Arguments

 `sample.size` the sample size of the binomial test (must be a positve integer) `alpha` the test I error-level of the test (must be between zero and one) `p0` the guessing probability under the null-hypothesis (must be between zero and one); 1/2 for the duotrio and twoAFC tests and 1/3 for the triangle, tetrad and threeAFC tests `pd0` the proportion of discriminators in the population of interest `test` the type of test

## Details

The critical value of the standard one-tailed difference test of "no difference" is obtained with `pd0 = 0`.

The probability of a correct answer under the null hypothesis is given by `pd0 + p0 * (1 - pd0)`.

## Value

The critical value in a one-tailed binomial test, that is, the smallest integer such that the null hypothesis binomial probability of being larger (smaller for similarity hypotheses) than or equal to this number is smaller than or equal to the type I error-level of the test.

## Author(s)

Rune Haubo B Christensen and Per Bruun Brockhoff

`triangle`, `twoAFC`, `threeAFC`, `duotrio`, `tetrad`, `discrim`, `discrimPwr`, `discrimSim`, `AnotA` `discrimSS`, `samediff`

## Examples

 ```1 2 3 4 5 6``` ```## Find the critical value for a triangle test for the level 0.05 test ## with 25 subjects: findcr(sample.size = 25, , p0 = 1/3) ## Similarity example: findcr(sample.size = 25, p0 = 1/3, pd0 = .2, test = "simil") ```

### Example output

```[1] 13
[1] 7
```

sensR documentation built on May 2, 2019, 9:43 a.m.