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, 07:26, 6 May 2013
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| == Covariate Correction (left-anchor and log tranformation)== | | == Covariate Correction (left-anchor and log tranformation)== |
− | For CPD we will consider the binned responses to be on a quantitative scale from 1-4 (see above under the CPD phenotype description). CPD therefore '''will not''' require transformation prior to covariate correction. | + | For CPD we will consider the binned responses to be on a quantitative scale from 1-4 (see above under the CPD phenotype description). '''CPD therefore will not require transformation''' prior to covariate correction. |
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− | For all other phenotypes (Pack Years, Smoking Initiation, Age of Initiation, Drinks Per Week) please '''left-anchor''' the distribution at 1 and '''log-transform it'''. (Left-anchoring, such that no value is less than 1, prevents the log-transform from returning nonsensical values like negative infinity). | + | For all other phenotypes (Pack Years, Smoking Initiation, Age of Initiation, Drinks Per Week) please '''left-anchor''' the distribution at 1 and '''log-transform it'''. (Left-anchoring, such that no value is less than 1, prevents the log-transform from returning nonsensical values like negative infinity). Then apply the covariate correction to the transformed phenotypes. |
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| Appropriate covariates can often be study-specific. We will depend on local investigators to determine the most appropriate covariates. We list here some covariates that will likely be necessary. | | Appropriate covariates can often be study-specific. We will depend on local investigators to determine the most appropriate covariates. We list here some covariates that will likely be necessary. |