expyfun.analyze.fit_sigmoid(x, y, p0=None, fixed=())[source]

Fit a sigmoid to summary data

Given a set of average values y (e.g., response probabilities) as a function of a variable x (e.g., presented target level), this will estimate the underlying sigmoidal response. Note that the fitting function can be sensitive to the shape of the data, so always inspect your results.


x-values along the sigmoid.


y-values at each location in the sigmoid.

p0array-like | None

Initial guesses for the fit. Can be None to estimate all parameters, or members of the array can be None to have these automatically estimated.

fixedlist of str

Which parameters should be fixed.

lower, upper, midpt, slopefloats

See expyfun.analyze.sigmoid for descriptions.