lsr (version 0.1.1)

cramersV: Cramer's V

Description

Calculate the Cramer's V measure of association

Usage

cramersV(...)

Arguments

...

Arguments to be passed to the chisq.test function.

Value

• A numeric variable with a single element corresponding to the value of V.

Warning

This function is under development. Some details may change in later versions.

Details

Calculates the Cramer's V measure of effect size for a chi-square goodness of fit test. The arguments to the cramersV function are all passed straight to the chisq.test function, and should have the same format.

See Also

chisq.test, assocstats (in the vcd package)

Examples

# Consider an experiment with two conditions, each with 100 
# participants. Each participant chooses between one of three
# options. Possible data for this experiment:

condition1 <- c(30, 20, 50) 
condition2 <- c(35, 30, 35)
X <- cbind( condition1, condition2 )
rownames(X) <- c( 'choice1', 'choice2', 'choice3' )
print(X)
#         condition1 condition2
# choice1         30         35
# choice2         20         30
# choice3         50         35
#

# To test the null hypothesis that the distribution of choices
# is identical in the two conditions, we would run a chi-square
# test:

chisq.test(X)
# 	Pearson's Chi-squared test
# 
# data:  X 
# X-squared = 5.0317, df = 2, p-value = 0.0808

# To estimate the effect size we can use Cramer's V:
cramersV( X )  # returns a value of 0.159