# How to use RevMan Calculator for GIV outcomes

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## 1. Select the GIV outcome

The calculator in RevMan Web can currently be used only for GIV outcomes.

Add a new analysis (see How to set up an analysis for more information). Under Options, Data Type, select ‘Generic Inverse Variance’.

## 2. Select the effect measure

Then, select the effect measure. Depending on the effect measure you choose, the interface of the calculator will be dynamically changed.

## 3. Add a data row

Once you add a data row (see How to set up an analysis for more information), the calculator will appear under Action button.

## 4. Do the calculation

You can use the calculator to get the measures you need for meta-analysis. For example, you can enter the odds ratio and its confidence interval and you will get the log odds ratio and standard error. Click on ‘Update Data table’ to enter the calculated values into the table.

Note that the calculator is currently not saving the input data. This means that when you open the calculator again, you will see only the calculated values (in this example, log odds ratio and standard error), but not the data you’ve initially entered to do the calculation (in this example, odds ratio and confidence interval).

## 5. Note the validation mechanisms

There are some validation mechanisms built in the RevMan Web calculator. For example, if you enter a negative value as the standard error, you will be alerted that the standard error must be bigger than zero. Similarly, you will be alerted if the p-value is not in the range from zero to one, or if the end value of the confidence interval is smaller than the start value.