How to Do the Calculations for a Confidence Interval Using Statlets

1. When you start Statlets, the following spreadsheet should appear. If not, click on the "File" pull down window and select "New."

2. Click on "Col_1" and the entire row should become shaded.

3. Type a new variable name, let's use "Weight" then press return: Then enter the following numbers, pressing return after each one:

2973

3193

2990

3077

3092

2996

2954

3006

3106

3077

4. Click on the "Analyze" menu, slide down to "One Sample" and slip over to "One Variable Analysis."

the following dialog box will appear:

5. Click on "Weight" then click on arrowhead that is pointing away from Weight.

6. Click on the "t-test" tab and the following should appear.

The 95%CI is (2992.93, 3099.87).

7. If you want another confidence inteval, say the 99%CI, click on the [Options] button.

Change the "Alpha:" from 5.0 to 1.0

Then press the [OK] button.

8. Now we want to save this output by either printing it or doing a screen capture.

To print, click on the "File" pull-down menu and select "Print." The following dialog box will appear.

Make sure that the radio button for "Current tab only" is selected as shown above, then press the "OK" button.

Instead of printing, or in addition to it, you can do a screen capture and then paste the screen image into a document. To do a screen capture, hold down the "Alt" key as you press the "Print Screen" key. This puts the active window (your results) in your computer's clipboard. Now, without closing Statlet, open your word processor (Word, Works, WordPerfect, etc) and do a paste (either Edit/Paste or hold down the "Ctrl" key as you press the "v" key). All the images in this tutorial were done using this method of screen capturing. Note: if you press the "Print Screen" key without pressing the "Alt" button, you will capture the entire screen and not just the active window (which is all we need to capture) for our purposes.