この節の作者: Ravi Selker, Jonathon Love, Damian Dropmann
Contingency Tables (contTables
)¶
Description¶
The X² test of association (not to be confused with the X² goodness of fit) is used to test whether two categorical variables are independent or associated. If the p-value is low, it suggests the variables are not independent, and that there is a relationship between the two variables.
Usage¶
contTables(
data,
rows,
cols,
counts = NULL,
layers = NULL,
chiSq = TRUE,
chiSqCorr = FALSE,
likeRat = FALSE,
fisher = FALSE,
contCoef = FALSE,
phiCra = FALSE,
logOdds = FALSE,
odds = FALSE,
relRisk = FALSE,
ci = TRUE,
ciWidth = 95,
gamma = FALSE,
taub = FALSE,
obs = TRUE,
exp = FALSE,
pcRow = FALSE,
pcCol = FALSE,
pcTot = FALSE,
formula
)
Arguments¶
data |
the data as a data frame |
rows |
the variable to use as the rows in the contingency table (not necessary when providing a formula, see the examples) |
cols |
the variable to use as the columns in the contingency table (not necessary when providing a formula, see the examples) |
counts |
the variable to use as the counts in the contingency table (not necessary when providing a formula, see the examples) |
layers |
the variables to use to split the contingency table (not necessary when providing a formula, see the examples) |
chiSq |
TRUE (default) or FALSE , provide X² |
chiSqCorr |
TRUE or FALSE (default), provide X² with continuity correction |
likeRat |
TRUE or FALSE (default), provide the likelihood ratio |
fisher |
TRUE or FALSE (default), provide Fisher's exact test |
contCoef |
TRUE or FALSE (default), provide the contingency coefficient |
phiCra |
TRUE or FALSE (default), provide Phi and Cramer's V |
logOdds |
TRUE or FALSE (default), provide the log odds ratio (only available for 2x2 tables) |
odds |
TRUE or FALSE (default), provide the odds ratio (only available for 2x2 tables) |
relRisk |
TRUE or FALSE (default), provide the relative risk (only available for 2x2 tables) |
ci |
TRUE or FALSE (default), provide confidence intervals for the comparative measures |
ciWidth |
a number between 50 and 99.9 (default: 95), width of the confidence intervals to provide |
gamma |
TRUE or FALSE (default), provide gamma |
taub |
TRUE or FALSE (default), provide Kendall's tau-b |
obs |
TRUE or FALSE (default), provide the observed counts |
exp |
TRUE or FALSE (default), provide the expected counts |
pcRow |
TRUE or FALSE (default), provide row percentages |
pcCol |
TRUE or FALSE (default), provide column percentages |
pcTot |
TRUE or FALSE (default), provide total percentages |
formula |
(optional) the formula to use, see the examples |
Output¶
A results object containing:
results$freqs |
a table of proportions |
results$chiSq |
a table of X² test results |
results$odds |
a table of comparative measures |
results$nom |
a table of the 'nominal' test results |
results$gamma |
a table of the gamma test results |
results$taub |
a table of the Kendall's tau-b test results |
Tables can be converted to data frames with asDF
or
as.data.frame()
. For example:
results$freqs$asDF
as.data.frame(results$freqs)
Examples¶
data('HairEyeColor')
dat <- as.data.frame(HairEyeColor)
contTables(formula = Freq ~ Hair:Eye, dat)
#
# CONTINGENCY TABLES
#
# Contingency Tables
# -----------------------------------------------------
# Hair Brown Blue Hazel Green Total
# -----------------------------------------------------
# Black 68 20 15 5 108
# Brown 119 84 54 29 286
# Red 26 17 14 14 71
# Blond 7 94 10 16 127
# Total 220 215 93 64 592
# -----------------------------------------------------
#
#
# X² Tests
# -------------------------------
# Value df p
# -------------------------------
# X² 138 9 < .001
# N 592
# -------------------------------
#
# Alternatively, omit the left of the formula (`Freq`) if each row
# represents a single observation:
contTables(formula = ~ Hair:Eye, dat)