Sample Size and Power for Two (K) Means with Unequal varianceHello,
Got a query regarding the DOE --> "Sample Size and Power".
Q1: Can it be used to calculate the sample size and power for two (or k) groups with an unequal variance? (below is sample data for 2 groups)
if Yes, then, how should I put in the "Std Dev"?
if No, is there an alternate solution for it? Thank you
Q2: There is also the "Power" option under "Fit Y by X", but it seems to use different parameters(see picture below), how to link these two platforms?
| Column 1 |
Column 2 |
| 13.41 |
-25.79 |
| 21.3 |
-3.87 |
| 10.26 |
4.14 |
| 10.67 |
-17.02 |
| 8.68 |
36.3 |
| 9.46 |
-33.83 |
| 6.8 |
22.37 |
| 6 |
-76.82 |
| 8.53 |
-4.42 |
| 12.56 |
-42.96 |
| 4.17 |
-0.62 |
| 13.92 |
-2.74 |
| 11.62 |
-19.87 |
| 9.71 |
-0.19 |
| 6.56 |
-20.43 |
| 7.53 |
-3.19 |
| 9.58 |
25.3 |
| 12.99 |
-10.98 |
| 9.13 |
17.26 |
| 8.4 |
-17 |
| 12.02 |
54.65 |
| 8.31 |
41.79 |
| 10.95 |
30.24 |
| 7.74 |
-5.17 |
| 6.83 |
-13.58 |
| 8.9 |
-0.02 |
| 10.84 |
7.84 |
| 10.86 |
4.81 |
| 9.27 |
9.19 |
| 10.47 |
-23.64 |
Stay Healthy!
PIn
Re: Sample Size and Power for Two (K) Means with Unequal variance- To use the tool you’d have to assume that variances are equal.
- Delta in Fit Y by X is not the same as the Difference to Detect in DOE’s Sample Size and Power, but there is some relationship:Delta= Difference to Detect / Sqrt(2k), where k is number of samples. So, the Difference to Detect=2*Delta for two-sample means.
Re: Sample Size and Power for Two (K) Means with Unequal varianceThank you Jian, your answer helps me to understand the delta setting ^-^
Meanwhile, I also found the jmp addin which was developed long time ago by Mark to dealing with an unequal variance situation.Re: Sample Size and Power for Two (K) Means with Unequal varianceFYI - There is a new platform in JMP 16, Sample Size Explorers, which can handle this. This platform will be in JMP 16 EA 2 (which will be available end of April).
Re: Sample Size and Power for Two (K) Means with Unequal varianceThank you Mia. I'd like to give it a try when available.
Have a wonderful week ^-^Re: Sample Size and Power for Two (K) Means with Unequal varianceMia,
Which one, Sample Size and Power for Two-sample Means with Unequal Variances, or Sample Size and Power for Testing Two Variances, will be added? Or both?Re: Sample Size and Power for Two (K) Means with Unequal varianceBoth - this is what it looks like now.
Power for Two Independent Sample Means includes an option for unequal standard deviations. As a bonus, there's also an option for unequal sample sizes.
Again, this will be featured in EA 2. We're actively recruiting for the EA program if you've got interested customers.
