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Incoming links: Variance of nested measurements
Pseudoreplication Created 2026-10-03 Updated 2026-10-18
Pseudoreplication treats dependent measurements from the same experimental unit as if they were independent treatment replicates. It exaggerates the effective sample size and commonly makes standard errors too small. In the pot example of replication in experimental design, counting twelve leaves per group as twelve independent treatment replicates ignores the four containing pots. The variance of nested measurements quantifies the resulting understatement of uncertainty. Nested measurements themselves are useful; pseudoreplication is the error of using them as independent replicates for the wrong level of inference.[ref]
Pseudoreplication and the Design of Ecological Field Experiments by Stuart H. Hurlbert. Pseudoreplication and the Design of Ecological Field Experiments, p. 190, definition, and p. 201, “Multiple samples per experimental unit”