Aggregate Data
KEY:
ds = dataset you are currently using.
DV = dependent variable of interest
IV = independent variable of interest
Subject = name of subject number column
XYXY = dummy name for a variable, matrix, or data frame into which you are moving information.
You have several trials of a dependent variable and you would like to get the mean scores at different levels of the independent variables.
Note: "DV1", "DV2", "IV1", "IV2" are names that you are giving to the columns (variables) in the aggregated data set. "DVa", "DVb", "IVa", "IVb" refer to the names in the data set you are collapsing.
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XYXY.agg <- aggregate (list (DV1 = ds$DVa, DV2 = ds$DVb),
by = list (Subject = ds$Subject,
IV1 = ds$IVa,
IV2 = ds$IVb),
FUN = mean, na.rm = TRUE)
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