Add Variance Inflation Factor

Add the variance inflation factor (VIF) or generalized VIF (GVIF) to the regression table. Function uses car::vif() to calculate the VIF.

Usage

add_vif(x, statistic = NULL, estimate_fun = label_style_sigfig(digits = 2))

Arguments

x

'tbl_regression' object

statistic

"VIF" (variance inflation factors, for models with no categorical terms) or one of/combination of "GVIF" (generalized variance inflation factors), "aGVIF" 'adjusted GVIF, i.e. GVIF^[1/(2*df)] and/or "df" (degrees of freedom). See car::vif() for details.

estimate_fun

Default is label_style_sigfig(digits = 2).

See also

Review list, formula, and selector syntax used throughout gtsummary

Examples

# Example 1 ----------------------------------
lm(age ~ grade + marker, trial) |>
  tbl_regression() |>
  add_vif()


  
Characteristic
      
Beta
      
95% CI1
      
p-value
      
GVIF1
      
Adjusted GVIF2,1
    
Grade






1.0
1.0
    I
—
—





    II
0.64
-4.7, 6.0
0.8



    III
2.4
-2.8, 7.6
0.4



Marker Level (ng/mL)
-0.04
-2.6, 2.5
>0.9
1.0
1.0
1 CI = Confidence Interval, GVIF = Generalized Variance Inflation Factor
    
2 GVIF^[1/(2*df)]
    

# Example 2 ----------------------------------
lm(age ~ grade + marker, trial) |>
  tbl_regression() |>
  add_vif(c("aGVIF", "df"))


  
Characteristic
      
Beta
      
95% CI1
      
p-value
      
Adjusted GVIF2,1
      
df1
    
Grade






1.0
2
    I
—
—





    II
0.64
-4.7, 6.0
0.8



    III
2.4
-2.8, 7.6
0.4



Marker Level (ng/mL)
-0.04
-2.6, 2.5
>0.9
1.0
1
1 CI = Confidence Interval, GVIF = Generalized Variance Inflation Factor, df = degrees of freedom
    
2 GVIF^[1/(2*df)]