Sample size effects in logistic regression.

A: Logistic model for Nursing Home Compare ‘Rehospitalized’ data and ‘1 star, 5 star’ overall rating. The moving average ‘5 star’ proportion is included for reference. The ‘5 star’ sample size proportion, , is shown as a horizontal line; n₁ = 1394, and n₅ = 2649. B: Normalized ‘5 star’ proportion adjusted for unequal sample sizes, and the adjusted logistic curve. The midpoint value, x₀ = 22.4, for the logistic curve is shown as a vertical line; the ‘Rehospitalized’ median is 22.2.