Inverse Variance Calculator

Turn study uncertainty into fair meta weights easily. Compare inputs, spot outliers, and summarize quickly. Download results, document methods, and report confident conclusions now.

Inputs
Study list and uncertainty
Use variance, standard error, or SD with sample size. Add effects if you want a pooled estimate.
Used only for pooled effect interval.
Affects display only, not exports.
You can leave effect cells blank anytime.
Tip: For SD+N mode, variance is SD²/N (variance of the mean).
Example data table
These values mirror the prefilled example and show how inputs map to variances and weights.
Study Input mode Given Derived variance Weight Effect
Study A Variance Var = 0.040 0.040 25.0000 0.52
Study B Standard error SE = 0.15 0.0225 44.4444 0.30
Study C SD + N SD = 1.20, N = 64 0.0225 44.4444 0.10
Formula used
How to use this calculator
  1. Add one row per study and choose an input mode.
  2. Provide variance, or provide standard error, or provide SD with sample size.
  3. Optionally enter each study’s effect size to compute a pooled estimate.
  4. Select a confidence level, then press Calculate.
  5. Review normalized weights and any row notes for data issues.
  6. Use Download CSV or Download PDF to export results.
FAQs
1) What is inverse variance weighting?
It assigns larger weights to more precise studies. Precision is represented by smaller variance, so weight equals one divided by variance.
2) Can I use standard errors instead of variances?
Yes. The calculator converts standard error to variance by squaring it, then computes the inverse variance weight.
3) What does SD with sample size mean here?
If you have a mean with SD and sample size, the variance of the mean is SD squared divided by the sample size.
4) Do I need effect sizes to calculate weights?
No. Weights only require variances. Effect sizes are needed only if you want the pooled fixed-effect estimate and its interval.
5) Why are normalized weights useful?
They show each study’s share of total influence. Normalized weights sum to one, making comparisons across studies straightforward.
6) What happens if a variance is zero or negative?
The row is flagged and excluded from calculations. Variance must be strictly positive to produce a meaningful inverse weight.
7) Is this the same as random-effects meta-analysis?
No. This tool computes fixed-effect inverse-variance weights. Random-effects methods add between-study variance, which changes weights.
8) What does the PDF export include?
It includes totals, optional pooled estimates, and a compact list of each study’s variance, weight, normalized weight, and effect if provided.

Note: This calculator provides statistical computations and does not replace professional analysis for critical decisions.

Related Calculators

number needed to treat calculatorheterogeneity test calculator

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.