「Missing data and imputation」の版間の差分
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!Missing not at random<br>MNAR | !Missing not at random<br>MNAR | ||
| − | |Missing depends on observed data | + | | |
| − | |Some participants intentionally deny to report higher body weights they don't like and only report lower body weights they like | + | *Missing depends on observed data |
| − | *Data of those participants are missed because of the values in the variable ''body weight'' themselves | + | | |
| + | *Some participants '''intentionally deny to report higher body weights they don't like''' and only report lower body weights they like | ||
| + | **Data of those participants are missed '''because of the values in the variable ''body weight'' themselves''' | ||
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!Missing at randam<br>MAR | !Missing at randam<br>MAR | ||
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| − | *Missing | + | *Missing does not depend on '''unobserved data''', but may depend on '''observed data''' |
| − | * | + | *The cause of missing can be explained by |
| − | |15% of female participants deny to report their body weights after the agreement regardless of measured body weights, but only 1% of male deny to report: | + | | |
| − | *Data of female participants are more likely missed not because of data (body weights) themselves but because female are more likely reluctant to report their body weights | + | *15% of female participants deny to report their body weights after the agreement regardless of measured body weights, but only 1% of male deny to report: |
| − | *In other words, values in the variable ''body weight'' themselves do not affect the missing but another variable ''sex'' affects the missing of values in the variable ''body weight'' | + | **Data of female participants are more likely missed not because of data (body weights) themselves but because female are more likely reluctant to report their body weights |
| + | **In other words, values in the variable ''body weight'' themselves do not affect the missing but another variable ''sex'' affects the missing of values in the variable ''body weight'' | ||
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!Missing completely at random<br>MCAR | !Missing completely at random<br>MCAR | ||
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| − | *Missing does NOT depend on '''observed data''' NOR on ''unobserved data'' | + | *Missing does NOT depend on '''observed data''' NOR on '''unobserved data''' |
*Missing occurs purely at random independely from any observed and unobserved data | *Missing occurs purely at random independely from any observed and unobserved data | ||
| − | |A participant moves to outside cohort area because of family affair which has nothing to do with the study and is lost to follow up at the 10th week: | + | | |
| − | *Data after the move are missed not because of data (body weights) themselves, nor because of the participant's unobserved (unmeasured) characteristic related to the study | + | *A participant moves to outside cohort area because of family affair which has nothing to do with the study and is lost to follow up at the 10th week: |
| + | **Data after the move are missed not because of data (body weights) themselves, nor because of the participant's unobserved (unmeasured) characteristic related to the study | ||
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2023年12月10日 (日) 14:24時点における版
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Three mechanisms (assumptions) of data missing
| Description | [*Example] A cohort study in which participants report their body weight every week to research center for 52 weeks in total | |
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| Missing not at random MNAR |
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| Missing at randam MAR |
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| Missing completely at random MCAR |
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