And even cooler logistic fitting function, will think of a better name later
logistic_sac(dat, y, time, params = NULL, startSamp = 8, ...)
subject data to be used
outcome variable
time variable
NULL
unless user wants to specify starting parameters for gnls
how many samples from distribution should we use to investigate
just in case
y ~ mini + (peak - mini) / (1 + exp(4 * slope * (cross - (time)) / (peak - mini)))