We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
When you do a stratified analysis to control for confounding you end up with a number of different odds ratios – one for each stratum. If these are all fairly similar, the next stage is to combine them into a single adjusted odds ratio that summarises the effect of the exposure adjusted for the confounder. Note that it is practical to do this only when you have a fairly small number of strata; once you need to adjust for more than one or two confounders it is better to use multivariable modelling techniques.
An adjusted odds ratio is essentially a weighted average of the stratum specific odds ratios. We calculate a weighted average rather than a straight average so that strata with more people (and therefore greater precision) have a bigger influence on the final result than small strata. To calculate a weighted average, each individual value is multiplied by its weight and these new values are then added up and divided by the sum of the weights. Various sets of weights can be used for pooling odds ratios, but those proposed by Mantel and Haenszel (1959) are commonly used.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.
