Automatic test for continuous variables for 2 groups. Variable names can be assigned using table1::label() function.
Arguments
- data
Data frame from which variables will be extracted.
- groupvar
Grouping variable as character. Must have exactly 2 levels.
- ttest_args
Arguments to be passed to
t.test()function.- wilcox_args
Arguments to be passed to
wilcox.test()function.- flextableformat
Logical operator to indicate the output desired. Default is TRUE. When FALSE, function will return a dataframe format.
- caption
TRUE/FALSE or character. If FALSE, no caption will be displayed. If TRUE, caption will be the same as groupvar or groupvar label. If character, character will be displayed as caption. For display options, flextableformat option must be TRUE.
Value
Returns a dataframe or flextable of 2 groups 2 sided Mann Whitney's U or T test, along with Shapiro-Wilk's p values and Levene's p value.
Examples
df <- mtcars
df$am <- as.factor(df$am)
continuous_2g(data = df,
groupvar = "am",
flextableformat = FALSE)
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Variable P_Shapiro_Resid P_Levene P_T_Test Var_Equal P_Mann_Whitney
#> 1 mpg 0.85734 0.04957 0.00137 FALSE 0.00187
#> 2 cyl <0.001* 0.96551 0.00215 TRUE 0.0039
#> 3 disp 0.22478 0.17931 <0.001* TRUE <0.001*
#> 4 hp 0.01338 0.67085 0.17983 TRUE 0.0457
#> 5 drat 0.02818 0.71856 <0.001* TRUE <0.001*
#> 6 wt 0.01854 0.98911 <0.001* TRUE <0.001*
#> 7 qsec 0.28471 0.57490 0.20566 TRUE 0.26574
#> 8 vs <0.001* 0.61223 0.35704 TRUE 0.3602
#> 9 gear <0.001* 0.29718 <0.001* TRUE <0.001*
#> 10 carb 0.00185 0.22233 0.75445 TRUE 0.73502
#> Diff_Means CI_Lower CI_Upper Significant_test
#> 1 -7.24494 -11.28019 -3.20968 Welch T test
#> 2 1.87045 0.73267 3.00822 Mann-W-U test
#> 3 146.84818 72.15611 221.54025 Student T test
#> 4 33.41700 -16.27768 83.11169 Mann-W-U test
#> 5 -0.76368 -1.04394 -0.48343 Mann-W-U test
#> 6 1.35789 0.83043 1.88536 Mann-W-U test
#> 7 0.82316 -0.47636 2.12268 None
#> 8 -0.17004 -0.54129 0.20121 None
#> 9 -1.17409 -1.50920 -0.83898 Mann-W-U test
#> 10 -0.18623 -1.39118 1.01871 None
# Set names to variables
if(requireNamespace("table1")){
table1::label(df$mpg) <- "Miles per gallon"
table1::label(df$cyl) <- "Number of cylinders"
table1::label(df$disp) <- "Displacement"
table1::label(df$hp) <- "Gross horsepower"
table1::label(df$drat) <- "Rear axle ratio"
continuous_2g(data = df, groupvar = "am", flextableformat = FALSE)
}
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Warning: cannot compute exact p-value with ties
#> Variable P_Shapiro_Resid P_Levene P_T_Test Var_Equal
#> 1 Miles per gallon 0.85734 0.04957 0.00137 FALSE
#> 2 Number of cylinders <0.001* 0.96551 0.00215 TRUE
#> 3 Displacement 0.22478 0.17931 <0.001* TRUE
#> 4 Gross horsepower 0.01338 0.67085 0.17983 TRUE
#> 5 Rear axle ratio 0.02818 0.71856 <0.001* TRUE
#> 6 wt 0.01854 0.98911 <0.001* TRUE
#> 7 qsec 0.28471 0.57490 0.20566 TRUE
#> 8 vs <0.001* 0.61223 0.35704 TRUE
#> 9 gear <0.001* 0.29718 <0.001* TRUE
#> 10 carb 0.00185 0.22233 0.75445 TRUE
#> P_Mann_Whitney Diff_Means CI_Lower CI_Upper Significant_test
#> 1 0.00187 -7.24494 -11.28019 -3.20968 Welch T test
#> 2 0.0039 1.87045 0.73267 3.00822 Mann-W-U test
#> 3 <0.001* 146.84818 72.15611 221.54025 Student T test
#> 4 0.0457 33.41700 -16.27768 83.11169 Mann-W-U test
#> 5 <0.001* -0.76368 -1.04394 -0.48343 Mann-W-U test
#> 6 <0.001* 1.35789 0.83043 1.88536 Mann-W-U test
#> 7 0.26574 0.82316 -0.47636 2.12268 None
#> 8 0.3602 -0.17004 -0.54129 0.20121 None
#> 9 <0.001* -1.17409 -1.50920 -0.83898 Mann-W-U test
#> 10 0.73502 -0.18623 -1.39118 1.01871 None