In: Statistics and Probability
Schools and museums: Do people who are interested in environment issues visit museums more often than people who are not? In 2012, the general social survey asked 1498 people how interested they were in environmental issues, and how often they had visited a science museum in the past year. The following table presents the results.
Number of Visits
None One More than one
Very Interested 513 138 58
Moderately Interested 459 98 34
Not Interested 163 20 15
Can you conclude that the number of visits to a science museum to interest in environmental issues? Use the a=0.05 level of significance and the P-Value method with the TI-84 Plus calculator.
(a) state the null and alternate hypotheses.
Ho: The number of visits to a science museum ________ related to interest in environmental issues.
H1: The number of visits to a science museum _______ related to interest in environmental issues.
The question of interest here is whether people exhibit interests in environmental issues, do visit science museums more often.
So basically, we are to determine if there is any relationship between the interest in environmental issues and museum visits. To do this, we shall use a Chi-square test.
The data provided for the same is:
None | One | More than One | TOTAL | |
Very Interested | 513 | 138 | 58 | 709 |
Moderately Interested | 459 | 98 | 34 | 591 |
Not Interested | 163 | 20 | 15 | 198 |
TOTAL | 1135 | 256 | 107 | 1498 |
The number of rows here is n1 = 3 and the number of columns is n2 = 3. Hence, the degrees of freedom are:
The significance level is set at 0.05.
Using a Chi-square table, we get a critical value of 9.488.
Now, we begin determining the Chi-square statistic for the given table.
First, we compute the expected values. To do this, we multiply the total of each row and each column and divide this by the grand total.
For example, the expected value of very interested and none becomes:
Doing this, for all the cells, we get the expectation table as:
None | One | More than One | TOTAL | |
Very Interested | 537.1929 | 121.1642 | 50.6429 | 709 |
Moderately Interested | 447.787 | 100.9987 | 42.2143 | 591 |
Not Interested | 150.02 | 33.8371 | 14.1429 | 198 |
TOTAL | 1135 | 256 | 107 | 1498 |
Next, we compute:
Doing so, we get:
None | One | More than One | |
Very Interested | 1.0895 | 2.3393 | 1.0688 |
Moderately Interested | 0.2808 | 0.089 | 1.5984 |
Not Interested | 1.1231 | 5.6584 | 0.0519 |
Now, the chi-square statistic is given by the formula:
Hence, summing all the values of the above table, we get:
Comparing this to the critical value, we have:
Hence, the ci-square statistic is greater than the critical value.
Therefore, we conclude at 0.05 significance level that there exists a relationship between the interest in environmental issues and the frequency with which people visit science museums.