R: power calculations for chi-squared tests

pwr.chisq.test {pwr} | R Documentation

## power calculations for chi-squared tests

### Description

Compute power of test or determine parameters to obtain target power (same as power.anova.test).

### Usage

    pwr.chisq.test(w = NULL, N = NULL, df = NULL, sig.level = 0.05, power = NULL)

### Arguments

`w` | Effect size
`N` | Total number of observations
`df` | degree of freedom (depends on the chosen test)
`sig.level` | Significance level (Type I error probability)
`power` | Power of test (1 minus Type II error probability)

### Details

Exactly one of the parameters 'w','N','power' and 'sig.level' must be passed as NULL, and that parameter is determined from the others. Notice that the last one has non-NULL default so NULL must be explicitly passed if you want to compute it.

### Value

Object of class '"power.htest"', a list of the arguments (including the computed one) augmented with 'method' and 'note' elements.

### Note

'uniroot' is used to solve power equation for unknowns, so you may see errors from it, notably about inability to bracket the root when invalid arguments are given.

### Author(s)

Stephane Champely <champely@univ-lyon1.fr> but this is a mere copy of Peter Dalgaard work (power.t.test)

### References

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale,NJ: Lawrence Erlbaum.

### See Also

ES.w1,ES.w2

### Examples

    ## Exercise 7.1 P. 249 from Cohen (1988)
    pwr.chisq.test(w=0.289,df=(4-1),N=100,sig.level=0.05)

    ## Exercise 7.3 p. 251
    pwr.chisq.test(w=0.346,df=(2-1)*(3-1),N=140,sig.level=0.01)

    ## Exercise 7.8 p. 270
    pwr.chisq.test(w=0.1,df=(5-1)*(6-1),power=0.80,sig.level=0.05)

[Package pwr version 1.2-2 Index]