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To Compute a Confidence Interval for the Difference Between Two Means (Independent Samples)
Press the right arrow key to scroll over to the TESTS menu.
Press the down arrow key to scroll down until 2-SampZInt or 2-SampTInt is highlighted (whichever is appropriate).
Specify whether you are using raw data, or stats (if you are using raw data, you need to enter that data into two of the lists, one for each sample, before attempting to create the interval).
If you’re using raw data, input the locations of the data, the frequency of the data points contained in each list (usually 1), the confidence level formatted as a decimal, and tell the calculator whether or not to use pooling, if necessary.
If you’re using stats, input the mean, standard deviation, and sample size for each of the two samples, the confidence level formatted as a decimal, and tell the calculator whether or not to use pooling, if necessary.
Highlight the word Calculate and press ENTER.
The calculator should now display the desired confidence interval.