Chi-Squared
o−ⅇ
2
χ =෎
ⅇ
2
Test to determine if
variation between o & e is
due to CHANCE or to the
VARIABLE you are testing.
Null Hypothesis = H0
states there is no
statistically significant
difference between the
o&e
o = observed data
e = expected data
df = degree of freedom
n = #of possible outcomes
df = n-1
Critical value determines whether the null
hypothesis is accepted or rejected
2
If your χ is less
than the critical value then
accept the H0
Therefore there is NO
statistical difference
between o & e
0.05
1df = 3.841
2df = 5.991
3df = 7.815
4df = 9.488
5df = 11.07
6df = 12.59
7df = 14.07
8df = 15.51
9df = 16.92
10df = 18.31
If your χ2 is greater
than the critical value then
reject the H0
Therefore the results are
due to variable tested
*not due to chance