In: Statistics and Probability
Smoking remains more common in much of Europe than in the United States. In the United States, there is a strong relationship between education and smoking: well-educated people are less likely to smoke. Does a similar relationship hold in France? Here is a two-way table of the level of education and smoking status (nonsmoker, former smoker, moderate smoker, heavy smoker) of a sample of 467 French men aged 20 to 60 years. The subjects are a random sample of men who visited a health center for a routine checkup. We are willing to consider them an SRS of men from their region of France.
Education | Smoking Status | ||||
Nonsmoker | Former | Moderate | Heavy | ||
Primary school | 58 | 53 | 41 | 38 | |
Secondary school | 39 | 42 | 28 | 32 | |
University | 53 | 27 | 38 | 18 |
The null hypothesis states that there is no relationship between these variables. That is, the distribution of smoking is the same for all three levels of education.
(a) Find the expected counts for each smoking status among men
with a university education. This is one row of the two-way table
of expected counts. Find the row total and verify that it agrees
with the row total for the observed counts.
Use two decimals for the expected counts and a whole number for the
total.
Education | Smoking Status | TOTAL | ||||
Nonsmoker | Former | Moderate | Heavy | |||
University | ||||||
Expected |
Part a
We are given observed frequencies as below:
Observed Frequencies |
|||||
Smoking Status |
|||||
Education |
Non-smoker |
Former |
Moderate |
Heavy |
Total |
Primary |
58 |
53 |
41 |
38 |
190 |
Secondary |
39 |
42 |
28 |
32 |
141 |
University |
53 |
27 |
38 |
18 |
136 |
Total |
150 |
122 |
107 |
88 |
467 |
Test statistic formula is given as below:
Chi square = ∑[(O – E)^2/E]
Where, O is observed frequencies and E is expected frequencies.
E = row total * column total / Grand total
For the first cell, expected frequency is given as below:
E = 150*190/467 = 61.03
In the same way, all expected frequencies are summarised in the following table:
Expected Frequencies |
|||||
Smoking Status |
|||||
Education |
Non-smoker |
Former |
Moderate |
Heavy |
Total |
Primary |
61.03 |
49.64 |
43.53 |
35.80 |
190 |
Secondary |
45.29 |
36.84 |
32.31 |
26.57 |
141 |
University |
43.68 |
35.53 |
31.16 |
25.63 |
136 |
Total |
150 |
122 |
107 |
88 |
467 |