AtlasSession 2L5: Introduction to Numerical Concepts in Researchp.47–58
Normal vs non-normal
Fig. 1
IL-6 (pg/mL) by ELISA in conditioned medium from MSC-seeded scaffolds
Fig. 1. A bell-shaped pile of 40 samples (IL-6), highest in the middle at 42 pg/mL and thinning out on both sides; one step of spread is 20 pg/mL.
- Middle
- 42 pg/mL
- One step of spread
- 20 pg/mL
Distribution Lab · First look
Level 1 · First look · Lecture 5 · p.47–58
Tell a lopsided pile of data from a balanced one and pick the right 'typical value' for each.
Judge normality from a histogram, box plot, Q-Q plot, KS test, skewness and kurtosis, then choose mean (SD) or median (quartiles).
Lopsided piles (the step you are on)
Household incomes bunch low with a few huge ones; IL-6 levels in culture medium do the same.
Like household incomes, IL-6 levels bunch at the low end with a few very high ones: a lopsided pile.