Result waves have a fixed name associated with the operation. Statistical test operations can print some of their results to the history window and save them in a wave in the current data folder. Some tables reflect a "convervative" approach and print the x-value of subsequent transitions. (1-alpha) in a vertical transition so one could use the x-value for the vertical transition as a critical value or the x-value of the subsequent vertical transition. In this case the CDF most likely attains the value Whenever possible Igor's tests provide exact critical values as well as the commonĬomparison of critical values with published table values can sometimes be interesting as there does not appear to be a standard forĭetermining the critical value when the CDF takes a finite number of discreet values (step-like). Fortunately, when parameters become large one can usually find an adequate approximate solution. In some distributions (e.g., Friedman's) the calculation of the CDF is so computationally intensive that it can be impractical Critical values are usually obtained from the inverse of the CDF for the appropriate distribution function, i.e., by They are by far the most difficult technicalĪspect in implementating statistical tests. Some tests compute the P-value which you can then directly compare to the desired significance value.Ĭritical values have been traditionally published in tables for various significance levels and tails of distributions. (default value 0.05 or specified via the /ALPH flag). Most tests compute a critical value for the given significance alpha In order to determine if you should accept or reject the test hypothesis (H 0). Test operations analyze the input data to examine the validity of a specific hypothesis.Ĭommon tests involves a computation of some numeric value, also known as "test statistic", which is usually compared with a critical value
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