Is there a difference between groups?
IL-6 differs between these pairs after correction: Drug A vs Control, Drug B vs Drug A.
One-way ANOVA: F(2, 33) = 41.90, p < 0.001
| Pair | Difference | p (Holm) | |
|---|---|---|---|
| Drug A vs Control | 24.37 | < 0.001 | **** |
| Drug B vs Control | 2.30 | 0.365 | ns |
| Drug B vs Drug A | -22.07 | < 0.001 | **** |
How to read this
- What the chart shows
- The box spans the middle half of the samples (first to third quartile) with the median as a thick line; whiskers reach the smallest and largest value. Brackets mark each pair with its corrected result.
- Data used
- All 36 samples: IL-6 (pg/ml), grouped by treatment (Control, Drug A, Drug B).
- Calculation
- With three groups: a one-way ANOVA, then a Welch t-test for every pair, corrected with Holm's method. With two groups: a single Welch t-test. Stars: **** p < 0.0001, *** < 0.001, ** < 0.01, * < 0.05, ns otherwise.
- How to read it
- A small p-value says the difference would be unusual if the groups were truly the same. It says nothing about why, and nothing about whether the difference matters biologically.
- Limits
- Assumes independent samples. With 12 samples per group, a single outlier can change the result. A clear difference is a reason to repeat the experiment, not a conclusion.
R code
Runs on the downloaded CSV and gives the numbers shown above.
d <- read.csv("scalar-demo-synthetic.csv")
d$treatment <- factor(d$treatment, levels = c("Control", "Drug A", "Drug B"))
summary(aov(IL6_pg_ml ~ treatment, data = d))
pairwise.t.test(d$IL6_pg_ml, d$treatment,
pool.sd = FALSE, p.adjust.method = "holm")


