sjstats (version 0.12.0)

grpmean: Summary of mean values by group

Description

Computes mean, sd and se for each sub-group (indicated by grp) of dv.

Usage

grpmean(x, dv, grp, weight.by = NULL, digits = 2)

Arguments

x

A (grouped) data frame.

dv

Name of the dependent variable, for which the mean value, grouped by grp, is computed.

grp

Factor with the cross-classifying variable, where dv is grouped into the categories represented by grp. Numeric vectors are coerced to factors.

weight.by

Vector of weights that will be applied to weight all cases. Must be a vector of same length as the input vector. Default is NULL, so no weights are used.

digits

Numeric, amount of digits after decimal point when rounding estimates and values.

Value

For non-grouped data frames, grpmean() returns a data frame with following columns: term, mean, N, std.dev, std.error and p.value. For grouped data frames, returns a list of such data frames.

Details

This function performs a One-Way-Anova with dv as dependent and grp as independent variable, by calling lm(count ~ as.factor(grp)), to get p-values for each sub-group and the complete "model". P-values indicate whether each group-mean is significantly different from the reference group (reference level of grp).

Examples

# NOT RUN {
data(efc)
grpmean(efc, c12hour, e42dep)

data(iris)
grpmean(iris, Sepal.Width, Species)

# also works for grouped data frames
library(dplyr)
efc %>%
  group_by(c172code) %>%
  grpmean(c12hour, e42dep)

# }