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Test whether a distribution is normal for each item

Source: R/effects.R
effect_metrics_items.Rd

The test is calculated using stats::shapiro.test.

Usage

effect_metrics_items(
  data,
  cols,
  adjust = "fdr",
  labels = TRUE,
  clean = TRUE,
  ...
)

Arguments

data

A tibble containing item measures.

cols

The column holding metric values.

adjust

Performing multiple significance tests inflates the alpha error. Thus, p values need to be adjusted according to the number of tests. Set a method supported by stats::p.adjust, e.g. "fdr" (the default) or "bonferroni". Disable adjustment with FALSE.

labels

If TRUE (default) extracts labels from the attributes, see codebook.

clean

Prepare data by data_clean.

...

Placeholder to allow calling the method with unused parameters from effect_metrics.

Value

A volker table containing itemwise statistics:

  • skewness: Measure of asymmetry in the distribution. A value of 0 indicates perfect symmetry.

  • kurtosis: Measure of the "tailedness" of the distribution.

  • W: W-statistic from the Shapiro-Wilk normality test.

  • p: p-value for the statistical test.

  • stars: Significance stars based on p-value (*, **, ***).

  • normality: Interpretation of normality based on Shapiro-Wilk test.

Examples

library(volker)
data <- volker::chatgpt

effect_metrics_items(data, starts_with("cg_adoption"))
#> 
#> 
#> |Expectations                             | skewness| kurtosis|    W|     p| stars|  normality|
#> |:----------------------------------------|--------:|--------:|----:|-----:|-----:|----------:|
#> |ChatGPT has clear advantages compared... |    -0.51|    -0.05| 0.89| 0.000|   ***| not normal|
#> |Using ChatGPT brings financial benefits. |     0.09|    -1.00| 0.90| 0.000|   ***| not normal|
#> |Using ChatGPT is advantageous in many... |    -0.76|    -0.02| 0.86| 0.000|   ***| not normal|
#> |Compared to other systems, using Chat... |    -0.66|     0.43| 0.86| 0.000|   ***| not normal|
#> |Much can go wrong when using ChatGPT.    |     0.12|    -0.85| 0.91| 0.000|   ***| not normal|
#> |There are legal issues with using Cha... |     0.07|    -0.66| 0.90| 0.000|   ***| not normal|
#> |The security of user data is not guar... |     0.22|    -0.61| 0.89| 0.000|   ***| not normal|
#> |Using ChatGPT could bring personal di... |     0.33|    -0.65| 0.91| 0.000|   ***| not normal|
#> |In my environment, using ChatGPT is s... |     0.39|    -0.68| 0.90| 0.000|   ***| not normal|
#> |Almost everyone in my environment use... |     0.56|    -0.51| 0.88| 0.000|   ***| not normal|
#> |Not using ChatGPT is considered being... |     1.08|     0.22| 0.79| 0.000|   ***| not normal|
#> |Using ChatGPT brings me recognition f... |     0.57|    -0.77| 0.87| 0.000|   ***| not normal|
#> 
#> 4 missing case(s) omitted. Adjusted significance p values with fdr method.
#>