outlier_report: Flag univariate and multivariate outliers

In surveyframe: Survey Instrument Workflows

Flag univariate and multivariate outliers

Description

Uses transparent screening rules for numeric survey response variables. The report supports data review before modelling, not automatic deletion.

Usage

outlier_report(
  data,
  variables = NULL,
  method = c("zscore", "iqr", "mahalanobis"),
  z_cut = 3,
  iqr_multiplier = 1.5,
  p_cut = 0.975
)

Arguments

data	A data.frame.
variables	Character vector of numeric variables to screen. When NULL, all numeric columns are used.
method	Outlier rule. "zscore" flags absolute z scores above z_cut; "iqr" flags values outside Tukey fences; "mahalanobis" flags rows above the chi-square cutoff for the selected variables.
z_cut	Numeric cutoff for "zscore". Defaults to 3.
iqr_multiplier	Numeric multiplier for "iqr" fences. Defaults to 1.5.
p_cut	Probability cutoff for "mahalanobis". Defaults to 0.975.

Value

An object of class sframe_outlier_report with the method, screened variables, a result table, flagged row numbers, and a reporting prompt.

Examples

demo <- sframe_demo_data()
outliers <- outlier_report(
  demo$responses,
  variables = c("dm_1", "dm_2", "sat_1"),
  method = "zscore"
)
outliers$flagged_rows

surveyframe documentation built on July 25, 2026, 1:07 a.m.