Hello David,

I think of the 'outcome', 'comparison' and 'intervention' codes as a way to filter your outcome data when you are running a meta-analysis. If you pre-define your 'outcome', 'comparison' and 'intervention' catagories by creating codes for each of them you can then select the appropriate category when entering you numeric outcome data and filter by those catagories when selecting which outcomes to include in your meta-analysis.

If you look at the example review that was placed under your account (when you created your account) you can see how they are used in the data extraction codeset (under 'Outcome / effectiveness data'). If you look at an item that has numeric outcome data entered (ex. Botherly (2001)) and go into one of the outcomes for that item you can see how the different catagories have been selected. Each of the pre-defined codes are in dropdown menus that you can select when entering your numeric outcome data.

All 'outcome', 'comparison' and 'intervention' codes have an outcome button so it doesn't matter which code you use to enter the outcome data. The outcome data is tied to the item and the 'outcome', 'comparison' and 'intervention' codes are just used to catagorise the outcome data.

Best regards,

Jeff