##### Biometry Chapter 6

Frequency

The number of times a particular value occurs or the number of times values in a stated range occur.

Expected frequency

The number of times you expect a particular value to occur based on the null hypothesis being tested.

One-way classification chi-square test

or

Goodness-of-fit chi-square test

It compares frequencies assigned according to a single set of categories in a simple frequency distribution to those expected based on some theoretical consideration

Two-way classification chi-square test

or

Test of association

or

Test of Independence

It compares frequencies assigned according to two sets of categories in an R x C contingency table frequency distribution to those expected based on no association between the two sets of categories.

Test of homogeneity

When all expected values are the same in a one-way chi-square test

Contingency table

A table where R is the number of rows (that is, the number of categories in one set) and C is the number of columns (this is, categories in the other set)

What is step one of the one-way chi-square test?

State the null hypothesis

What is step two of the one-way chi-square test?

Choose a critical significance level

What is step three of the one-way chi-square test?

Calculate the test statistic (X^{2})

*Degrees of freedom = number of categories - 1

What is step four of the one-way chi-square test?

Reject or accept the null hypothesis

What is step one of the two-way chi-square test?

State the null hypothesis

What is step two of the two-way chi-square test?

Choose the critical significance level

What is step three of the two-way chi-square test?

Calculate the test statistic (X^{2})

*Degrees of freedom = (# of rows - 1)x(# of columns - 1)

What is step four of the two-way chi-square test?

Accept or reject your null hypothesis