For numeric data, you need only three numbers, count, mean, and standard deviation, to compute a confidence interval for a mean. If you have these three numbers, you can type them directly into the estimate mean object.
1. Create a new estimate by dragging one from the shelf or choosing Object | New | Interval Estimate.
2. From the pop-up menu in the estimate's upper-right corner, choose Estimate Mean.
3. Double-click the bold, blue field AttributeName in the body of the estimate, and type a reasonable name.
4. Press Tab to move to the next field and continue inputting appropriate values.
As you enter values, the text changes throughout the estimate object.
This estimate shows a computation of the confidence interval for a sample of 9 scores with a mean of 120 and a standard deviation of 15. Notice that because the estimate is in verbose mode, it describes in detail the meaning of a confidence interval.
Key Curriculum Press/Key College Publishing www.keypress.com/fathom |