Apps. and Interpretation for IBDP Maths Ebook 1 | Page 341

Chapter
23
Statistical Tests
SUMMARY POINTs
�
2
� test for independence, for a contingency table with r rows and c columns:
n � rc : Total number of data
O ( i�
1, 2, , n): Observed frequencies
i
E ( i�
1, 2, , n): Expected frequencies
i
v � ( r �1)( c � 1) : Degree of freedom
�
2
calc
n
2
( Oi
� Ei)
� � :
E
i�1
i
2
� test statistic
C : Critical value in the hypothesis test
H
0
: Null hypothesis
H
1: Alternative hypothesis
23
�
Decision rule for
2
� test for independence:
H
0
: Two variables are independent
H
1: Two variables are not independent
H
0
is rejected if
� � C or the p -value is less than the significance level
2
calc
H
0
is not rejected if
level
� � C or the p -value is greater than the significance
2
calc
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