Data Pilot - Comparing Averages
The bootstrap method allows comparing averages of the subsamples in order to determine the probability of one average is higher than the other. The sizes of the subsamples may differ.
Sometimes, confidence intervals are used for comparing averages, but this is the wrong approach. There are instances when 90% confidence intervals coincide, yet one average is larger than the other with very high probability. One of such cases is described below.
Subsamples from 3-4 observation can be used only for the preliminary data analysis. In order to approach the confidence probability of 0.99 you have to have at least 8 data points in two subsamples.
After indicating the basic data area and the results area, select from the dropdown menu “Confidence Interval” and press the "Next >>" button.
Select here the number of iterations. More iterations mean higher precision level for the results and longer calculations time.
The "<< Back" button allows users to come back to the original data and calculation method selection.
Press the “Calc” button to start calculations.
During the process of calculation, a progress window appears. The “Cancel” button allows user to stop the calculations. After the calculation is complete, you get the results.
You can compare the results you got with the Confidence Interval. Despite the fact that 90% confidence intervals for “C Mag” and “M 49” coincide, the average for “M 49” is higher than the average for “C Mag” with the probability of 98%