# 8.1.1.2.2 - Example with Summarized Data

8.1.1.2.2 - Example with Summarized Data

## Example: Dieting

At the beginning of the Fall 2016 semester a representative sample of World Campus STAT 200 students was surveyed. The students were asked if they were currently dieting to lose weight. In the sample of 524 students, 184 said that they were dieting to lose weight. Construct a 95% confidence interval for the proportion of all World Campus STAT 200 students who are dieting to lose weight.

In Minitab, select Stat > Basic Statistics > 1-Proportion
1. In this case we have summarized data so select Summarized data in the dropdown.
2. For number of events, add 184 and for number of trials add 524.
3. Select Options
4. The default Confidence level is 95.
5. Change the Method to Normal approximation because the assumption of $$n \widehat p \geq 10$$ and $$n(1- \widehat p) \geq 10$$ has been met
6. Click OK and OK.

This should result in the following output:

#### Method

p: event proportion

Normal approximation is used for this analysis.

Descriptive Statistics
N Event Sample p 95% CI for p
524 184 0.351145 (0.310276, 0.392015)

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