Science with Dr. Kostenko - How to use the Chi-Square Test for analyzing data

•Used to determine if there is a significant difference between the expected and observed data

•Null hypothesis: There is NO statistically significant difference between expected & observed data

•Any differences are due to CHANCE alone

x²= E (o-e)² / e

1.Determine null hypothesis

•All frequencies are equal –OR– Specific frequencies given already

2.Use formula to calculate χ2 value:

•n = # of categories, e = expected, o = observed

3.Find critical value using table (Use p=0.05).

•degrees of freedom (df) = n – 1

4.If χ2 < Critical Value, then ACCEPT null hypothesis. Differences in data are due to chance alone.

If χ2 > Critical Value, REJECT the null hypothesis: Differences in data are NOT due to chance alone!

critical values:

Google Sites

Report abuse