Wednesday, December 5 Chi-square Test of Independence: Two Variables. Summing up!
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Transcript of Wednesday, December 5 Chi-square Test of Independence: Two Variables. Summing up!
Wednesday, December 5
Chi-square Test of Independence: Two Variables.Summing up!
Chi-square Test of Independence
Are two nominal level variables related or independentfrom each other?
Is race related to SES, or are they independent?
15
32
1928 47
Lo
Hi
SES
White Black
Row n x Column n
Total n
The expected frequency of any given cell is
15
32
1928 47
(15x28)/47 (15x19)/47
(32x28)/47 (32x19)/47
8.94 6.06
19.06 12.94
15
32
1928 47
Lo
Hi
SES
White Black
12 3
16 16
15
32
1928 47
8.94 6.06
19.06 12.94
12 3
16 16
2 =(fo - fe)2
fe
r=1
r
c=1
c
Please calculate:
Bivariate Statistics
Nominal Ordinal Interval
Nominal 2 Rank-sum t-testKruskal-Wallis H ANOVA
Ordinal Spearman rs (rho)
Interval Pearson rRegression
Y
X
Who said this?
"The definition of insanity is doing the same thing over and over again and expecting different results".
Who said this?
"The definition of insanity is doing the same thing over and over again and expecting different results".
• I don’t like it because from a statistical point of view, it is insane to do the same thing over and over again and expect the same results!
• More to the point, the wisdom of statistics lies in understanding that repeating things some ways ends up with results that are more the same than others. Hmm. Think about this for a moment. Statistics allows one to understand the expected variability in results even when the same thing is done, as a function of σ and N.
Your turn!
• If I take a sample of N=1, why can’t I make inferences to the larger population from this sample?
Your turn!
• If I take a sample of N=1, why can’t I make inferences to the larger population from this sample? What does Guinness have to do with it?