Transcript Chi-square or X 2

Concerned with testing:
Two factors: Test of Independence
Whether or not a set of data fits a
particular distribution: Goodness-ofFit Test
Chi-square or X 2
Continuous distribution
Generally, skewed to the right (long right tail)
Shape changes when the dfs change (df =
degrees of freedom and depends on the sample
size) df = 2
df = 24
Chi-square or X 2
When the dfs are 90 or more, the chi-square
curve and normal curve are almost the same.
Mean and Standard Deviation
μ = the # of dfs
_________
σ = √2(# of dfs)
Example: For a chi-square distribution
with df = 45,
μ = 45
_____
σ = √2(45) = 9.4868