In: Statistics and Probability
An researcher wishes to see if the primary way people obtain information is independent of their highest level of education. A survey of 400 high school and college graduates yielded the following information. At the = 0.05 significance level, test the claim that the way people obtained information is independent of their education level.
- A clear statement of hypotheses
- An indication of the test being used
- Statement of the test statistic and either
p-value (or appropriate critical value)
- Explicit statement of the statistical decision,
along with a reason
- A specific conclusion based on the statistical
decision.
TV | Newspaper | Other | |
HighsSchool | 163 | 30 | 52 |
College | 37 | 65 | 53 |
Null hypothesis : Ho : The way people obtained information is independent of their education level. (or way people obtained information and their education level are not associated)
Alternative Hypothesis : Ha: The way people obtained information is dependent of their education level.(or way people obtained information and their education level are associated)
Chi-square test for Association
Test Statistic
O : Observed Frequency
E: Expected Frequency
Given: Observed frequency : O
Observed Counts/Frequency | TV | Newspaper | Other | Row Total |
HighsSchool | 163 | 30 | 52 | 245 |
College | 37 | 65 | 53 | 155 |
Column Total | 200 | 95 | 105 | 400 |
E: Expected Count/Frequency | TV | Newspaper | Other |
HighsSchool | (245*200) / 400 | (245*95) / 400 | (245*105) / 400 |
College | (155*200) / 400 | (155*95) / 400 | (155*105) / 400 |
E: Expected Count/Frequency | TV | Newspaper | Other |
HighsSchool | 122.5000 | 58.1875 | 64.3125 |
College | 77.5000 | 36.8125 | 40.6875 |
O | E | O-E | (O-E)2 | |
163 | 122.5000 | 40.5000 | 1640.2500 | 13.3898 |
30 | 58.1875 | -28.1875 | 794.5352 | 13.6547 |
52 | 64.3125 | -12.3125 | 151.5977 | 2.3572 |
37 | 77.5000 | -40.5000 | 1640.2500 | 21.1645 |
65 | 36.8125 | 28.1875 | 794.5352 | 21.5833 |
53 | 40.6875 | 12.3125 | 151.5977 | 3.7259 |
Total | 75.8755 |
Test Statistic
Value of the test statistic = 75.8755
Degrees of freedom = (Number of rows - 1) x (Number of columns - 1) =(2-1)x(3-1)=1x2=2
For 2 degrees of freedom,
p-value = 0.0000
Level of significance : = 0.05;
Critical value of : for 2 degrees of freedom = 5.991
Statistical decision:
As p-value:0.0000 < Level of significance : : 0.05; Reject the null hypothesis.
As Value of the test statistic : 78.8755 > Critical value : 5.991 ; Reject the null hypothesis.
Specific conclusion :
At 0.05 significance level there is sufficient evidence to conclude that the way people obtained information is dependent of their education level.