Pairwise tests of independence for tables with one ordered nominal variable

Conducts pairwise tests for a 2-dimensional table, in which one variable is ordered nominal and one variable is non-ordered nominal. The function relies on the coin package.

pairwiseOrdinalIndependence(
  x,
  compare = "row",
  scores = NULL,
  method = "fdr",
  digits = 3,
  ...
)

Arguments

x

A two-way contingency table. One dimension is ordered and one is non-ordered nominal.

compare

If "row", treats the rows as the grouping variable. If "column", treats the columns as the grouping variable.

scores

Optional vector to specify the spacing of the ordered variable.

method

The method to adjust multiple p-values. See stats::p.adjust.

digits

The number of significant digits in the output.

...

Additional arguments, passed to stats::chisq_test.

Value

A data frame of comparisons, p-values, and adjusted p-values.

Author

Salvatore Mangiafico, mangiafico@njaes.rutgers.edu

Examples

### Independence test for table with one ordered variable
data(Breakfast)
require(coin)
chisq_test(Breakfast,
           scores = list("Breakfast" = c(-2, -1, 0, 1, 2)))
#> 
#> 	Asymptotic Generalized Pearson Chi-Squared Test
#> 
#> data:  Breakfast (ordered) by Travel (Walk, Bus, Drive)
#> chi-squared = 8.6739, df = 2, p-value = 0.01308
#> 
PT = pairwiseOrdinalIndependence(Breakfast, compare = "row")
PT
#>     Comparison p.value p.adjust
#> 1   Walk : Bus 0.12800   0.1570
#> 2 Walk : Drive 0.00462   0.0139
#> 3  Bus : Drive 0.15700   0.1570
cldList(comparison = PT$Comparison, 
        p.value    = PT$p.value, 
        threshold  = 0.05)
#>   Group Letter MonoLetter
#> 1  Walk      a         a 
#> 2   Bus     ab         ab
#> 3 Drive      b          b
        
### Similar to Kruskal-Wallis test for Likert data
data(PoohPiglet)
XT = xtabs(~ Speaker + Likert, data = PoohPiglet)
XT
#>         Likert
#> Speaker  1 2 3 4 5
#>   Piglet 1 6 2 1 0
#>   Pooh   0 0 1 6 3
#>   Tigger 0 0 2 6 2
require(coin)
chisq_test(XT,
           scores = list("Likert" = c(1, 2, 3, 4, 5)))
#> 
#> 	Asymptotic Generalized Pearson Chi-Squared Test
#> 
#> data:  Likert (ordered) by Speaker (Piglet, Pooh, Tigger)
#> chi-squared = 18.423, df = 2, p-value = 9.991e-05
#> 
PT=pairwiseOrdinalIndependence(XT, compare = "row")
PT
#>        Comparison  p.value p.adjust
#> 1   Piglet : Pooh 0.000310 0.000902
#> 2 Piglet : Tigger 0.000601 0.000902
#> 3   Pooh : Tigger 0.474000 0.474000
cldList(comparison = PT$Comparison, 
        p.value    = PT$p.value, 
        threshold  = 0.05)         
#>    Group Letter MonoLetter
#> 1 Piglet      a         a 
#> 2   Pooh      b          b
#> 3 Tigger      b          b