lags.fnc: Calculate vector at specified lag

In languageR: Analyzing Linguistic Data: A Practical Introduction to Statistics

Description

This function calculates for a given dependent variable the value of that variable at lag timesteps earlier in the time series of an experiment.

Usage

lags.fnc(dat, time="Trial", group = "Subject", depvar = "RT", lag=1)

Arguments

dat	A data frame with (minimally) a grouping factor, an time index for successive trails/events, and a behavioral measure
group	A grouping factor such as Subject
time	A sequential time index measure such as Trial number in an experimental list
depvar	The dependent variable, usually a chronometric measure such as RT
lag	The lag for which previous values are to be extracted

Value

A vector with the values of the dependent variable at the specified lag. The by-group mean is substituted for the first lag timestep(s), for which there is/are no preceding value(s) for the dependent variable.

Author(s)

R. H. Baayen

See Also

acf.fnc

Examples

## Not run: 
  dfr = data.frame(Subject=c(rep("a", 5), rep("b", 5)),
                   Trial = c(rep(1:5,2)),
                   RT = rnorm(10, 500, 40))
  dfr$prevRT = lag.fnc(dfr, time="Trial", group="Subject", depvar="RT")
  dfr


## End(Not run)

languageR documentation built on May 2, 2019, 10:02 a.m.