Variance Inflation Factor Calculator
Translates an auxiliary regression R² into the variance inflation associated with predictor collinearity. The worked condition keeps the method and source values visible for an independent check.
Describe the observed data during an independent check
Variance inflation factor
The quantity this page defines at the chosen parameter values
Construct a second plausible scenario that changes one uncertain input while keeping the rest coherent. Compare the statistic and the practical interpretation across both cases. The page-specific quantity is variance inflation factor.
If a small defensible change reverses the conclusion, report the sensitivity rather than hiding it behind one preferred scenario. The chosen variance inflation factor convention remains attached to the source record. Before reusing variance inflation factor, write down the observed scale, the model boundary, and the convention behind the displayed value. A short record of that kind makes it possible to distinguish a changed dataset from a changed definition, and it gives the next analyst a clear route back to the original calculation.
Evidence beside the calculation before comparing groups
Translates an auxiliary regression R² into the variance inflation associated with predictor collinearity. The displayed relationship is VIF = 1/(1−R²aux), and each symbol is tied to a labeled field. The page-specific quantity is variance inflation factor.
An auxiliary R² of 0.75 gives VIF=4. This example is a numerical check of the method, not proof that the model describes every dataset. The chosen variance inflation factor convention remains attached to the source record. Before reusing variance inflation factor, write down the observed scale, the model boundary, and the convention behind the displayed value. A short record of that kind makes it possible to distinguish a changed dataset from a changed definition, and it gives the next analyst a clear route back to the original calculation.
How to carry the result forward when the result is reused
A VIF is a diagnostic whose interpretation depends on design, scaling, and the other predictors; no universal cutoff proves a problem. The page-specific quantity is variance inflation factor.
The unit of analysis, exposure, sample boundary, and treatment of missing or tied values stay outside the answer unless they are explicitly entered. Keep those choices beside this regression result. The chosen variance inflation factor convention remains attached to the source record.
For a related question, compare regression f statistic and partial correlation.
Reading the inputs in the worked condition
Check the scales and domains before evaluating variance inflation factor. Counts, probabilities, rates, logarithms, and squared units are not interchangeable merely because a field accepts a number.
If one input changes, predict the direction of the result from the formula first. That simple check catches reversed groups, an incorrect parameterization, and percentage values entered on the wrong scale. The chosen variance inflation factor convention remains attached to the source record.
Interpreting the result before reporting in this example
Recalculate one intermediate quantity from VIF = 1/(1−R²aux) and work back from the displayed answer. The source values should be sufficient for another analyst to reproduce variance inflation factor without guessing a convention.
Use a boundary case when possible: equal paired values, a probability near zero, a zero slope, or a rate of zero. The expected limiting behavior is often more informative than another decimal place. The chosen variance inflation factor convention remains attached to the source record.
A controlled alternative under the stated model in this example
The number answers one statistical question. It does not establish causation, model fit, representativeness, or a useful decision threshold by itself. The page-specific quantity is variance inflation factor.
Practical meaning depends on the measurement scale and consequences. State the comparison or benchmark before presenting variance inflation factor as evidence.
The scale of the reported number when the sample changes
A VIF is a diagnostic whose interpretation depends on design, scaling, and the other predictors; no universal cutoff proves a problem. Outliers, dependence, sparse observations, extrapolation, or a mismatched parameterization can change the appropriate reference method. The page-specific quantity is variance inflation factor.
Choose an alternative because the design or data require it, not because its result is more favorable. Preserve the selected convention in the report. The chosen variance inflation factor convention remains attached to the source record.
Before reporting this result when the result is reused
For the saved dataset, does this result prove a causal relationship for this calculation?
No. Statistical association or model arithmetic does not replace design, measurement, or substantive reasoning. The reported quantity here is variance inflation factor.
At the stated exposure, what belongs in the saved record?
Preserve the source data or summaries, formula convention, units, exclusions, and method version. The reported quantity here is variance inflation factor.
When the fitted range moves, what should be checked before reusing this result?
Keep the inputs, units, model name, exclusions, and unrounded output together. The reported quantity here is variance inflation factor.
During an independent check, why might another program return a different number?
Parameterization, tie rules, tail conventions, rounding, or distributional approximations can differ. The reported quantity here is variance inflation factor.
For the worked condition, when should the calculation be repeated?
Repeat it when an input, sample boundary, group definition, or model assumption changes. The reported quantity here is variance inflation factor.