Section author: Ravi Selker, Jonathon Love, Damian Dropmann

Descriptives (descriptives)

Description

Descriptives are an assortment of summarising statistics, and visualizations which allow exploring the shape and distribution of data. It is good practice to explore your data with descriptives before proceeding to more formal tests.

Usage

descriptives(
  data,
  vars,
  splitBy = NULL,
  freq = FALSE,
  hist = FALSE,
  dens = FALSE,
  bar = FALSE,
  barCounts = FALSE,
  box = FALSE,
  violin = FALSE,
  dot = FALSE,
  dotType = "jitter",
  qq = FALSE,
  n = TRUE,
  missing = TRUE,
  mean = TRUE,
  median = TRUE,
  mode = FALSE,
  sum = FALSE,
  sd = TRUE,
  variance = FALSE,
  range = FALSE,
  min = TRUE,
  max = TRUE,
  se = FALSE,
  skew = FALSE,
  kurt = FALSE,
  sw = FALSE,
  quart = FALSE,
  pcEqGr = FALSE,
  pcNEqGr = 4,
  formula
)

Arguments

data	the data as a data frame
vars	a vector of strings naming the variables of interest in data
splitBy	a vector of strings naming the variables used to split vars
freq	TRUE or FALSE (default), provide frequency tables (nominal, ordinal variables only)
hist	TRUE or FALSE (default), provide histograms (continuous variables only)
dens	TRUE or FALSE (default), provide density plots (continuous variables only)
bar	TRUE or FALSE (default), provide bar plots (nominal, ordinal variables only)
barCounts	TRUE or FALSE (default), add counts to the bar plots
box	TRUE or FALSE (default), provide box plots (continuous variables only)
violin	TRUE or FALSE (default), provide violin plots (continuous variables only)
dot	TRUE or FALSE (default), provide dot plots (continuous variables only)
dotType	.
qq	TRUE or FALSE (default), provide Q-Q plots (continuous variables only)
n	TRUE (default) or FALSE, provide the sample size
missing	TRUE (default) or FALSE, provide the number of missing values
mean	TRUE (default) or FALSE, provide the mean
median	TRUE (default) or FALSE, provide the median
mode	TRUE or FALSE (default), provide the mode
sum	TRUE or FALSE (default), provide the sum
sd	TRUE (default) or FALSE, provide the standard deviation
variance	TRUE or FALSE (default), provide the variance
range	TRUE or FALSE (default), provide the range
min	TRUE or FALSE (default), provide the minimum
max	TRUE or FALSE (default), provide the maximum
se	TRUE or FALSE (default), provide the standard error
skew	TRUE or FALSE (default), provide the skewness
kurt	TRUE or FALSE (default), provide the kurtosis
sw	TRUE or FALSE (default), provide Shapiro-Wilk p-value
quart	TRUE or FALSE (default), provide quartiles
pcEqGr	TRUE or FALSE (default), provide quantiles
pcNEqGr	an integer (default: 4) specifying the number of equal groups
formula	(optional) the formula to use, see the examples

Output

A results object containing:

results$descriptives	a table of the descriptive statistics
results$frequencies	an array of frequency tables

Tables can be converted to data frames with asDF or as.data.frame(). For example:

results$descriptives$asDF

as.data.frame(results$descriptives)

Examples

data('mtcars')
dat <- mtcars

# frequency tables can be provided for factors
dat$gear <- as.factor(dat$gear)

descriptives(dat, vars = vars(mpg, cyl, disp, gear), freq = TRUE)

#
#  DESCRIPTIVES
#
#  Descriptives
#  -------------------------------------------
#               mpg     cyl     disp    gear
#  -------------------------------------------
#    N            32      32      32      32
#    Missing       0       0       0       0
#    Mean       20.1    6.19     231    3.69
#    Median     19.2    6.00     196    4.00
#    Minimum    10.4    4.00    71.1       3
#    Maximum    33.9    8.00     472       5
#  -------------------------------------------
#
#
#  FREQUENCIES
#
#  Frequencies of gear
#  --------------------
#    Levels    Counts
#  --------------------
#    3             15
#    4             12
#    5              5
#  --------------------
#

# spliting by a variable
descriptives(formula = disp + mpg ~ cyl, dat,
    median=F, min=F, max=F, n=F, missing=F)

# providing histograms
descriptives(formula = mpg ~ cyl, dat, hist=T,
    median=F, min=F, max=F, n=F, missing=F)

# splitting by multiple variables
descriptives(formula = mpg ~ cyl:gear, dat,
    median=F, min=F, max=F, missing=F)