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, 09:42, 6 May 2013
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| 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). Then apply the covariate correction to the transformed phenotypes. | + | For the other four quantitative phenotypes (Pack Years, 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. This step is unnecessary for the binary smoking initiation phenotype |
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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. |