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One Sample Sign Test Help

The One Sample Sign Test method is based on collecting a number of samples from a population with unknown median, m. The median is used in place of the average because the median is a better measure of the central tendency of the data than the average for non-normal data. The example below shows how to do this test using the SPC for Excel software.

Example (from Statistics and Data Analysis, by Ajit Tamhane and Dorothy Dunlop, Prentice-Hall, 2000)

A thermostat is used in an electrical device to check to the accuracy of the design setting of 200 °F. Ten thermostats were tested to determine their actual settings. The results are given below.

202.2, 203.4, 200.5, 202.5, 206.3, 198.0, 203.7, 200.8, 201.3, 199.0

We want to use these results to see if the median setting is significantly different from the design setting of 200.

One Sample Sign Test Output

The output from the One Sample Sign Test is shown below.

The null hypothesis (m is median) and the alternate hypothesis (two sided in this example) are listed at the top.

The conclusions, based on value of p and alpha, are given. Reject the null hypothesis if p value < alpha.


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