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. 2022 May 5;20(5):e3001564. doi: 10.1371/journal.pbio.3001564

Fig 1.

Fig 1

(a) Overview of the study design. To examine reproducibility of research findings across laboratories, the same animal experiment was independently repeated in 3 laboratories in both a conventionally standardised (red) and a heterogenised design (blue). In the standardised design, mice of 2 strains, C57BL/6J and DBA/2N (n = 12 per strain), were tested by one experimenter, while in the heterogenised design, 3 different experimenters were involved in conducting the experiment (i.e., 4 mice per strain and experimenter were included in the analysis). Each experimenter, regardless of the design, conducted the same animal experiment following the same standardised protocols. All test procedures were conducted in the same order for all animals. (b) Experimental setup in each laboratory. In each laboratory, 4 experimenters conducted the same animal experiment as described above. All 4 experiments were conducted according to a randomised block design including 3 blocks per experiment (Block 1–3). In each block, mice were housed in the same row in the same rack (e.g., top, middle, bottom) and, thus, these animals shared the same environmental background with respect to lighting conditions, humidity, and temperature. Out of these 4 experiments per laboratory, one was randomly selected and classified as standardised experiment (e.g., Exp A, red). For the heterogenised design, one block (i.e., 4 mice per strain) from each of the remaining 3 experimenters (Exp B–Exp D) was pseudo-randomly selected and classified as part of a heterogenised experiment. This was done in a way that in each heterogenised experiment all 3 blocks were represented. Please note: Shown is one example of a possible allocation of experimenters and blocks to the standardised and heterogenised design, respectively (for details, see “Data analysis” and S3 Table). Furthermore, only mice of one strain (half of the mice tested) are visualised in the figure. DL, Dark Light; EPM, Elevated Plus Maze; FCMs, faecal corticosterone metabolites; NC, Novel Cage; NT, Nest; OF, Open Field; PND, postnatal day.