Chapter 7

Hypothesis Testing Applied to Means


Typical Questions:

The Central Limit Theorem

Testing Hypotheses about Single Means when the Population Variance is Known

Testing Hypotheses about Single Means when the Population Variance is Unknown

Example:

Testing Hypotheses Concerning Pairs of Means: Matched Samples

Difference Scores

Female TA
Male TA
Difference
Prof 1
15
10
5
Prof 2
22
20
2
Prof 3
18
19
-1
Prof 4
5
4
1
Prof 5
40
33
7
Prof 6
20
20
0
Prof 7
14
16
-2
Prof 8
10
14
-4
Prof 9
22
10
12
Prof 10
18
13
5
Mean
18.4
15.9
2.5
SD
4.67

Testing Hypotheses Concerning Pairs of Means: Independent Samples

Data from our "Memory Bias" experiment

Group
Mean
SD
Smashed into
74.0
9.06
Ran into
67.20
10.555
Made Contact with
66.30
11.22

The Variance Sum Law

Pooling Variances & Unequal Ns

Coupla Notes

Hetrogeneity of Variance:


Hypothesis Testing with Means: The Cookbook

One Mean vs. One population mean

Population variance known:

df = N-1

Population variance unknown:

df = N-1

Two Means

Matched samples:

df = N-1

Independent samples:

df = N1+N2-2

Examples