* A comparison of power analysis methods for evaluating effects of a predictor on slopes in longitudinal designs with missing data.
- In many longitudinal studies, evaluating the effect of a binary or continuous predictor variable on the rate of change of the outcome, i.e. slope, is often of primary interest. Sample size determination of these studies, however, is complicated by the expectation that missing data will occur due to missed visits, early drop out, and staggered entry. Despite the availability of methods for assessing power in longitudinal studies with missing data, the impact on power of the magnitude and distribution of missing data in the study population remain poorly understood. As a result, simple but erroneous alterations of the sample size formulae for complete/balanced data are commonly applied. These 'naive' approaches include the average sum of squares and average number of subjects methods. The goal of this article is to explore in greater detail the effect of missing data on study power and compare the performance of naive sample size methods to a correct maximum likelihood-based method using both mathematical and simulation-based approaches. Two different longitudinal aging studies are used to illustrate the methods.
=>1.〜に慣れて, 2.用いられた, 中古の
Overview of verb use
The verb use has 6 senses (first 3 from tagged texts)
1. (603) use, utilize, utilise, apply, employ -- (put into service; make work or employ for a
particular purpose or for its inherent or natural purpose; "use your head!"; "we only use Spanish at
home"; "I can't use this tool"; "Apply a magnetic field here"; "This thinking was applied to many
projects"; "How do you utilize this tool?"; "I apply this rule to get good results"; "use the
plastic bags to store the food"; "He doesn't know how to use a computer")
2. (12) use, habituate -- (take or consume (regularly or habitually); "She uses drugs rarely")
3. (8) use, expend -- (use up, consume fully; "The legislature expended its time on school
questions")
4. use -- (seek or achieve an end by using to one's advantage; "She uses her influential friends to
get jobs"; "The president's wife used her good connections")
5. practice, apply, use -- (avail oneself to; "apply a principle"; "practice a religion"; "use care
when going down the stairs"; "use your common sense"; "practice non-violent resistance")
6. use -- (habitually do something (use only in the past tense); "She used to call her mother every
week but now she calls only occasionally"; "I used to get sick when I ate in that dining hall";
"They used to vacation in the Bahamas")
Overview of adj used
The adj used has 3 senses (first 3 from tagged texts)
1. (4) used -- (employed in accomplishing something; "the principle of surprise is the most used and
misused of all the principles of war"- H.H.Arnold & I.C.Eaker)
2. (1) exploited, ill-used, put-upon, used, victimized, victimised -- (of persons; taken advantage
of; "after going out of his way to help his friend get the job he felt not appreciated but used")
3. (1) secondhand, used -- (previously used or owned by another; "bought a secondhand (or used)
car")
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