Describe stats::aov results

stats::aov() models containing Error() return an aovlist object, which cannot be passed to car::Anova(). This method extracts the ANOVA tables from each error stratum and reports effects using the residual degrees of freedom from the same stratum.

Usage

# S3 method for class 'aov'
apa(obj, term, sstype = 2, ...)

# S3 method for class 'aovlist'
apa(obj, term = NULL, f.digits = 2, ...)

Arguments

obj

fitted stats::aov model with an Error() term

term

model term to describe. A character term name or sequential number can be supplied; if NULL, all testable effects are returned.

sstype

anova SS type (e.g., 2 or 3)

...

other parameters passed to format_results

f.digits

number of digits for the F value

Value

formatted string with F(df_numerator, df_denominator) = F_value, p =/< p_value

one or more formatted strings with F, numerator and denominator df, and p values

Examples

if (requireNamespace("car", quietly = TRUE)) {
  # Using the mtcars dataset
  fit <- aov(mpg ~ cyl * am, data = mtcars)
  print(apa(fit, 'cyl'))
  print(apa(fit, 'am'))
  print(apa(fit, 'cyl:am'))

  # Using a different SS type
  print(apa(fit, 'cyl', sstype = 3))
}
#> [1] "_F_(1, 28) = 52.03, _p_ < .001"
#> [1] "_F_(1, 28) = 4.28, _p_ = .048"
#> [1] "_F_(1, 28) = 3.41, _p_ = .076"
#> [1] "_F_(1, 28) = 19.40, _p_ < .001"
fit_rm <- aov(yield ~ N * P * K + Error(block), data = npk)
apa(fit_rm, "N")
#>                                N 
#> "_F_(1, 12) = 12.26, _p_ = .004" 
apa(fit_rm)
#>                            N:P:K                                N 
#>   "_F_(1, 4) = 0.48, _p_ = .525" "_F_(1, 12) = 12.26, _p_ = .004" 
#>                                P                                K 
#>  "_F_(1, 12) = 0.54, _p_ = .475"  "_F_(1, 12) = 6.17, _p_ = .029" 
#>                              N:P                              N:K 
#>  "_F_(1, 12) = 1.38, _p_ = .263"  "_F_(1, 12) = 2.15, _p_ = .169" 
#>                              P:K 
#>  "_F_(1, 12) = 0.03, _p_ = .863"