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Apr 6, 2009 6:33 AM
(1498 views)

Does anyone know if JMP will give you MSD value (minimum significant difference) for a multiple comparison test (i.e. Tukey's HSD)? If so please let me know how to get it. THANKS!

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Yesterday
(45 views)

Solution

The minimum significant difference is not the same for all pairwise comparisons unless the sample sizes for all groups are equal. When sample sizes are not equal, then the minimum significant difference will vary from comparison to comparison.

If you are using the Fit Y by X platform (Oneway Analysis), you can determine the minimum significant difference as described earlier. When you do the comparisons, you will get an LSD or HSD Threshold Matrix which is the absolute value fo the difference minus the LSD or HSD. From the red triangle menu, you can obtain the Difference Matrix. You can use these together to determine the LSD or HSD.

In the Fit Model platform, you will get a matrix of the LSMeans Differences for the multiple comparison method chosen. In that case the test statistic (Q for Tukey or t for Student's t) is shown above the matrix and the standard error of the difference is shown in each cell of the matrix. If you multiply the test statistic by the standard error of the difference, you obtain the minimum significant difference (LSD or HSD).

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Apr 6, 2009 2:54 PM
(1340 views)

When you are doing multiple comparison test, you get the table called

Abs(Dif) - LSD

To get the LSD value subtract the value from the table above from the difference between the means found in the difference matrix in the same window.

Hope this helps...

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Aug 1, 2010 8:49 PM
(1340 views)

Thanks

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Aug 2, 2010 12:40 AM
(1340 views)

The cutoff level is normally alpha=0.05, but you can change that - see this thread for details: http://support.sas.com/forums/thread.jspa?messageID=29987産

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Aug 3, 2010 10:49 AM
(1340 views)

I follow expanding the tabs, but I am still confused:

1. From the LSMeans Student's T tab, how is SED calculated from the LSmeans below the matrix shown?

2. Once the SED is calculated, how do you calculate LSD?

I often use the letters chart, but if I have many response variables I get an alphabet soup of information that can be unwieldy in a paper, which is why I sometimes just prefer to include an LSD value.

I guess I am still surprised that JMP doesn't just have a function to give you an immediate value for SED and LSD when you have many response variables.

Many thanks!

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Yesterday
(46 views)

The minimum significant difference is not the same for all pairwise comparisons unless the sample sizes for all groups are equal. When sample sizes are not equal, then the minimum significant difference will vary from comparison to comparison.

If you are using the Fit Y by X platform (Oneway Analysis), you can determine the minimum significant difference as described earlier. When you do the comparisons, you will get an LSD or HSD Threshold Matrix which is the absolute value fo the difference minus the LSD or HSD. From the red triangle menu, you can obtain the Difference Matrix. You can use these together to determine the LSD or HSD.

In the Fit Model platform, you will get a matrix of the LSMeans Differences for the multiple comparison method chosen. In that case the test statistic (Q for Tukey or t for Student's t) is shown above the matrix and the standard error of the difference is shown in each cell of the matrix. If you multiply the test statistic by the standard error of the difference, you obtain the minimum significant difference (LSD or HSD).