The Spearman’s Rho Table shows a critical value of .447 for alpha = .05 and n = 20 and .522 for alpha = .02 and n = 20, so what value should we use when alpha = .025 and n = 20?
We will consider two approaches: linear interpolation and harmonic interpolation.
Linear Interpolation
With linear interpolation, the value we are looking for is calculated by
which can also be calculated using the Real Statistics formula
=INTERPOLATE(.025,.02,.05,.522,.447,FALSE)
Here the FALSE argument indicates that linear interpolation is being used.
Harmonic Interpolation
With harmonic interpolation, the value we are looking for is calculated by
which can also be calculated using the Real Statistics formula
=INTERPOLATE(.025,.02,.05,.522,.447,TRUE)
Here the TRUE argument indicates that harmonic interpolation is being used.
Table Lookup Functions
We give access to both forms of interpolation in the calculations of RhoCRIT, TauCRIT, MCRIT, WCRIT, DCRIT, LCRIT, KSCRIT, QCRIT, DLowerCRIT, DUpperCRIT and SRankCRIT, with the default being harmonic interpolation. For example
RhoCRIT(20,.025,2,TRUE) = .497 RhoCRIT(20,.025,2,FALSE) = .5095
Hi Charles,
I am confused on how to work the interpolation.
My W = 0.9162, n = 4, the W is 0.792 for 0.1 and 0.935 for 0.5.
How do I find out my p value?
Jessica,
Which type of interpolation would you like to use? Two types are described on the referenced webpage.
Charles
Hi
How to manually calculate pvalue interpolated if W is 0.927 for 0.05 and 0.939 for 0.1
It depends on the actual W value. If, for example W = .930, then using linear interpolation,
p-value = .05 + (.1-.05)*(.930-.927)/(.939-.927).
Charles