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POWER SIMULATION -- prev_f_full   [metric: # successes (count)]
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model: behavior ~ stim + day + stim:day + (1|rat)   (behavior = # successes (count); day within-window)
observed groups: stim n=12, control n=12   nrep=120, alpha=0.05
ground truth: stim:day=+0.5602/day, rat SD=4.316, residual SD=4.489, days=10

 true stim:day interaction = +0.5602 (100% of observed)
  N/group  | per-animal power | LME power
  ------------------------------------------
  3        |  0.13            |  0.27
  5        |  0.30            |  0.41
  8        |  0.53            |  0.59
  12       |  0.76            |  0.79  <- observed
  16       |  0.91            |  0.93
  24       |  0.98            |  0.98

 true stim:day interaction = +0.2801 (50% of observed)
  N/group  | per-animal power | LME power
  ------------------------------------------
  3        |  0.04            |  0.07
  5        |  0.12            |  0.14
  8        |  0.17            |  0.23
  12       |  0.33            |  0.35  <- observed
  16       |  0.33            |  0.37
  24       |  0.45            |  0.47

Read the per-animal column as the honest power; LME is optimistic (obs-level DF).