# The Combined Error Corrected Index Calculates the combined error corrected index ```r CECI(x, Ya, Yb, Yab, Ynull, w, psi, E, plot = F) ``` ## Arguments - `x`: Number of times individuals a and b were observed together - `Ya`: Number of times individual a was observed without b - `Yb`: Number of times individual b was observed without a - `Yab`: Number of times individuals a and b were observed at the same time but not associating - `Ynull`: Number of times neither a or b were observed - `w`: The correction term w (see details) - `psi`: The correction term psi (see details) - `E`: The correction term Epsilon (see details) - `plot`: Flag whether to plot the results or not (default = FALSE) ## Details The CECI calculates the probability that two individuals are observed together given that one has been seen, correcting for group location error (missing entire groups during a sampling period) and individual identification error (missing individuals that are present in a group). This index can be used if prior information is available on the observation probability of finding groups, where the correction factor w is based on calibration data suggesting that failing to observe a group containing both a and b when they are together is w times more (w > 0) or less (w < 0) likely than failing to observe both the group containing a and the group containing b when a and b are apart. E (Epsilon) is probability of missing one individual given that it is not with the other, which also requires calibration data. psi represents the relative importance of the group location error to the individual identification error (see Hoppitt & Farine in prep for how to calculate this value based on observation errors). ## Returns Returns two elements: the estimated association strength and the standard error of the estimate. Also plots the function if required. ## References Hoppitt, W. & Farine, D.R. (in prep) Association indices for quantifying social relationships: how to deal with missing observations of individuals or groups. ## Author(s) William Hoppitt Damien Farine ## Examples ```r # Simulated values x <- ya <- yb <- yab <- 10 ynull <- 0 # Set parameters to make equivalent to the SRI psi <- 1.0 w <- 0 E <- 0 # Calculate the group location error corrected index CECI(x,ya,yb,yab,ynull,w,psi,E) ```

CECI function