## Problem 279 — rank:290

**Title:** Reproducibility of engineered biology

**Added binding assumptions (LaTeX):**

```latex
Declare the probability distribution over new laboratories and whether laboratory effects are fixed or random. Small between-laboratory variance can coexist with a shared bias, so also anchor corrected means to independent standards and preserve predefined design contrasts. Mean-zero constraints or reference controls are needed to separate lab offsets from design-by-lab effects. Repeated instrument reads do not supply independent culture replication.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.