Chi Squared Flashcards
What is chi squared?
An non-parametric inferential statistical test
What kind of data is involved?
Nominal data
What does it measure?
Tests whether or not a pattern of observations is statistically significant
How is degrees of freedom calculated?
n-1
What are the main assumption?
- Nominal data
- More than 20 observations
- Cannot have 20% or more with exp. frequency <5
- No category with exp. frequency <1
- Frequencies, not percentages
What is the procedure
- Hypotheses
- Determine confidence level
- Calculate X squared
- Calculate degrees of freedom
- Determine significance level
What are observed values?
Frequency counts observed - one per category
What are expected values?
Frequency counts expected if H0 were true
If the sample represents the population what are we likely/unlikely to calculate?
Chi <1 is very likely
Chi >5 is very unlikely
If X squared exceeds the critical value, what happens next?
Move forward with the alternative hypothesis
Whats different about comparing samples?
- Degrees of freedom
- Expected values calculate for all categories in all samples
ei = (total row*total column)/Grand total