Summarize observations, predictions and errors in a PMop object made by makeOP,
usually in the `$data`

field of a PM_op object.

## Arguments

- object
A PMop object made by makeOP.

- digits
Integer, used for number of digits to print.

- pred.type
Either 'post' for a posterior object or 'pop' for a population object. Default is 'post'.

- icen
Can be either "median" for the predictions based on medians of

`pred.type`

parameter value distributions, or "mean". Default is "median".- outeq
Output equation number. Default is 1.

- ...
Not used.

## Value

A list with three elements.

sumstat A data frame with the minimum, first quartile, median, third quartile, maximum, mean and standard deviation for times, observations and predictions in

`x`

.pe A named vector with mean prediction error (mpe), the mean weighted prediction error (mwpe), the mean squared prediction error (mspe), root mean sqaured error (rmse), percent root mean squared error (percent_rmse), the mean weighted squared prediction error (mwspe), the bias-adjusted mean squared prediction error (bamspe), and the bias- adjusted mean weighted squared prediction error (bamwspe). The mwpe is bias and the bamwspe is imprecision on plots of PM_op objects.

wtd.t A list of 6 elements based on a t test that the weighted mean prediction bias is different than zero

estimate: the weighted mean of the prediction bias for each observation

se: the standard error of the estimate

conf.int: the 95% confidence interval of the mean

statistic: the t statistic of the standardized difference between mean and zero

df: degrees of freedom equal to number of observations minus one

p.value: the probability that the weighted mean is different than zero