Describe a Variable by a Factor with Two Levels

This function describes a numeric variable by a grouping factor with two levels. First, a descriptive text listing the frequencies and means of the two groups and the results of the significance test is generated. The results of Desc(x~g) are reported as they are provided by the function, followed by a plot consisting of a density plot and a box plot. This description makes sense, for example, if the age distribution of a collective is to be represented for both sexes. 

TwoGroups(x, ..., plotit = TRUE)

# Default S3 method
TwoGroups(x, g, main = NULL, vname = NULL, ..., plotit = TRUE)

# S3 method for class 'formula'
TwoGroups(formula, data, subset, na.action, ...)

# S3 method for class 'TwoGroups'
ToWrd(x, font = NULL, ..., wrd = DescToolsOptions("lastWord"))

Arguments

x

the numeric variable to describe.

g

the grouping factor (preferably with two levels.)

main

the main title.

vname

the variable names used in the description text.

plotit

boolean. Should a plot be created? Default can be defined by DescToolsOptions(plotit=TRUE/FALSE), if it does not exist then it's set to FALSE.

formula

a formula of the form lhs ~ rhs where lhs gives the data values and rhs the corresponding groups.

data

an optional matrix or data frame (or similar: see model.frame) containing the variables in the formula formula. By default the variables are taken from environment(formula).

subset

an optional vector specifying a subset of observations to be used.

na.action

a function which indicates what should happen when the data contain NAs. Defaults to getOption("na.action").

font

the first font will be chosen for the introducing text, when sending the output to Word, the second for the description.

wrd

the pointer to a running MS Word instance, as created by GetNewWrd() (for a new one) or by GetCurrWrd() for an existing one. Default is NULL, which will report all results to the console.

...

the dots are sent to the internally used function Phrase(). They can be used to choose the language (lang) or provide variable name (xname).

Value

list with the results calculated by the used functions

Author

Andri Signorell <andri@signorell.net>

Examples

x <- d.pizza$temperature
g <- factor(d.pizza$rabate)

# we can change the colors for the plot by setting the DescToolsOptions
DescToolsOptions(col=c(DescTools::horange, DescTools::hgreen))
TwoGroups(x, g, main="Temperature ~ Rebate")
#> Temperature ~ Rebate 
#> 
#> The entire group consists of a total of 1'158 elements. Of these, 580 are FALSE (50.1%, mean x 46.9) and 578 TRUE (49.9%, mean x 49.0).
#> The difference is significant (t-test, p = 2.12e-04) and is -2.15 [-3.29, -1.02] (95% CI). 
#> 
#> ────────────────────────────────────────────────────────────────────────────── 
#> Temperature ~ Rebate
#> 
#> Summary: 
#> n pairs: 1'209, valid: 1'158 (95.8%), missings: 51 (4.2%), groups: 2
#> 
#>                     
#>         FALSE   TRUE
#> mean     46.9   49.0
#> median   49.4   50.7
#> sd       10.2    9.5
#> IQR      13.6   12.5
#> n         580    578
#> np      50.1%  49.9%
#> NAs        21     18
#> 0s          0      0
#> 
#> Welch Two Sample t-test:
#>   t = -4, df = 1149, p-value = 0.0002
#> 
#> 
#> Warning:
#>   Grouping variable contains 12 NAs (0.993%).
#> 


# for an output to Word simply define the wrd argument
# wrd <- GetNewWrd()
# TwoGroups(x, g, font.desc=list(name="Consolas", size=8),
#           main="Temperature ~ Rebate", wrd=wrd)