Solve for the sample size required to achieve a target statistical power

This function estimates the sample size required to achieve a specified target statistical power using a fitted GAM/SCAM power model. The function first attempts to solve for the sample size using a root-finding algorithm. If the root-finding procedure fails, a grid-based interpolation method is used as a fallback to obtain an approximate solution.

Usage

ss_solver(
  target_power,
  logmean,
  abs_lfc,
  model,
  xmin = log2(5),
  xmax = log2(500)
)

Arguments

target_power

Numeric value specifying the desired statistical power.

logmean

Numeric value representing the log mean abundance.

abs_lfc

Numeric value representing the absolute log fold change.

model

A fitted GAM/SCAM model used to predict statistical power.

xmin

Numeric value giving the minimum log2(sample size) considered in the search. Default is log2(5).

xmax

Numeric value giving the maximum log2(sample size) considered in the search. Default is log2(500).

Value

A numeric value representing the estimated sample size required to achieve the target power.

Details

The function first attempts to compute the required sample size using a root-finding approach implemented in uniroot_ss(). If this method fails (for example, due to numerical issues or if the root cannot be bracketed within the specified interval), the function falls back to a grid-based interpolation approach implemented in sample_size_ss_interp().

A warning is issued if the target power is specified as 0 or 1, since these values correspond to unrealistic design targets in most practical applications.