Chapter 2 Technical vs biological variation

2.1 Technical variation

Examples:

• different sequencing depths (library sizes)
• batch effects (day, reagent, operator)
• gene length and GC content biases

We aim to control/correct these.

2.2 Biological variation

Differences due to the biology we care about:

• condition, tissue, genotype
• treatment, disease status

Normalization should reduce technical variation while leaving biological variation intact.