Experimental design considerations - Answer Key

Author

Will Gammerdinger

Published

November 12, 2025

Exercise 1

Your experiment has three different treatment groups, A, B, and C. Due to the lengthy process of tissue extraction, you can only isolate the RNA from two samples at the same time. You plan to have 4 replicates per group. Your metadata table is as follows:

sample treatment sex replicate RNA isolation
sample1 A F 1
sample2 A F 2
sample3 A M 3
sample4 A M 4
sample5 B F 1
sample6 B F 2
sample7 B M 3
sample8 B M 4
sample9 C F 1
sample10 C F 2
sample11 C M 3
sample12 C M 4

Click here to download the above table as an Excel file.

  1. Fill in the RNA isolation column of the metadata table. Since we can only prepare 2 samples at a time and we have 12 samples total, you will need to isolate RNA in 6 batches. In the RNA isolation column, enter one of the following values for each sample: group1, group2, group3, group4, group5, group6. Make sure to fill in the table so as to avoid confounding by batch of RNA isolation.
sample treatment sex replicate RNA isolation
sample1 A F 1 group1
sample2 A F 2 group2
sample3 A M 3 group3
sample4 A M 4 group4
sample5 B F 1 group3
sample6 B F 2 group5
sample7 B M 3 group1
sample8 B M 4 group6
sample9 C F 1 group4
sample10 C F 2 group6
sample11 C M 3 group2
sample12 C M 4 group5
  1. BONUS: To perform the RNA isolations more quickly, you devote two researchers to perform the RNA isolations. Create a researcher column and fill in the researchers’ initials for the samples they will prepare: use initials AB or CD.
sample treatment sex replicate RNA isolation Researcher
sample1 A F 1 group1 AB
sample2 A F 2 group2 CD
sample3 A M 3 group3 AB
sample4 A M 4 group4 CD
sample5 B F 1 group3 AB
sample6 B F 2 group5 CD
sample7 B M 3 group1 AB
sample8 B M 4 group6 CD
sample9 C F 1 group4 CD
sample10 C F 2 group6 AB
sample11 C M 3 group2 CD
sample12 C M 4 group5 AB

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