「Missing data and imputation」の版間の差分
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*'''15% of female participants denied to report''' their body weights after participation '''regardless of measured body weights''', but only 1% of male denied to report | *'''15% of female participants denied to report''' their body weights after participation '''regardless of measured body weights''', but only 1% of male denied to report | ||
*Researchers can identify that female participants more likely denied to report body weights than male | *Researchers can identify that female participants more likely denied to report body weights than male | ||
| − | **Missing occurred | + | **Missing occurred NOT because of body weights themselves but '''because of another variable ''sex''''' |
**Missing mechanism is at random, i.e., free from missing values only inside each participant but NOT at random, i.e., NOT free from variable ''sex'' | **Missing mechanism is at random, i.e., free from missing values only inside each participant but NOT at random, i.e., NOT free from variable ''sex'' | ||
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*A participant '''moved to outside cohort area''' because of family affair and was lost to follow up | *A participant '''moved to outside cohort area''' because of family affair and was lost to follow up | ||
*A participant '''failed to report body weights because of malfunction of the app''' | *A participant '''failed to report body weights because of malfunction of the app''' | ||
| − | **Missing occurred | + | **Missing occurred NOT because of body weights themselves NOR other variables |
**Missing mechanism is completely at random, i.e., completely free from both of missing (unobserved) values and observed values in body weight or in other variables | **Missing mechanism is completely at random, i.e., completely free from both of missing (unobserved) values and observed values in body weight or in other variables | ||
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2023年12月10日 (日) 16:13時点における版
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Three mechanisms (assumptions) of data missing
| Abbr. | Missing depends on/ Missing occurs because of |
[Example] A cohort study in which participants self report their body weight every week via special app installed on their smartphones. Demographic variables are also collected. | ||
|---|---|---|---|---|
| missing value itself | other observed variable(s) | |||
| Missing not at random | MNAR | YES | — |
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| Missing at randam | MAR | NO | YES |
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| Missing completely at random | MCAR | NO | NO |
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