Math Problem Statement
Pollsters want to test if an association exists between a person’s profession and their political party. A random sample of 295295 voters is polled, resulting in the data in the following table. Based on these results, is there enough evidence at the 0.010.01 level of significance to say that an association exists? Observed Sample of VotersDemocratRepublicanTotalDoctor
45
22
67
Lawyer
22
19
41
Teacher
36
38
74
Farmer
44
24
68
Laborer
28
17
45
Total
175
120
295 Calculate the expected value for the number of doctors voting for the Democratic party. Round your answer to six decimal places.
Solution
We are tasked with calculating the expected value for the number of doctors voting for the Democratic party using a contingency table for a chi-square test of independence.
Given dataWe are tasked with calculating the expected value for the number of doctors voting for the Democratic party using a contingency table for a chi-square test of independence.
Given
Profession | Democrat | Republican | Total |
---|---|---|---|
Doctor | 45 | 22 | 67 |
Lawyer | 22 | 19 | 41 |
Teacher | 36 | 38 | 74 |
Farmer | 44 | 24 | 68 |
Laborer | 28 | 17 | 45 |
Total | 175 | 120 | 295 |
We are asked to compute the expected value for the number of doctors voting for the Democratic party.
Formula for Expected Value:
The formula to calculate the expected value for a cell in a contingency table is:
Here:
- Row total for doctors: 67
- Column total for Democrats: 175
- Grand total: 295
Substituting these values into the formula:
Let's calculate that.The expected value for the number of doctors voting for the Democratic party is approximately 39.745763.
Would you like further details or have any questions about the calculations?
Here are some related questions:
- How do we interpret the chi-square test of independence?
- What is the next step in conducting the full chi-square test for this data?
- How do you compute the chi-square statistic for the entire table?
- What is the significance level and how is it applied in hypothesis testing?
- Can this test determine causation or just association?
Tip: Always ensure the assumptions of a chi-square test are met, such as having expected frequencies greater than 5 in each cell.
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Math Problem Analysis
Mathematical Concepts
Statistics
Chi-Square Test
Contingency Tables
Formulas
Expected Value Formula: E_ij = (Row Total × Column Total) / Grand Total
Theorems
Chi-Square Test of Independence
Suitable Grade Level
Grades 11-12 (Statistics/Pre-College Level)
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