sleepstudy 데이터셋
lme4::sleepstudy()
data(sleepstudy, package="lme4")'데이터 > 패키지에 있는 데이터 > 첨부된 패키지에서 데이터셋 읽기...' 메뉴 기능을 선택하면 하위 선택 창으로 이동한다. 아래와 같이 lme4 패키지를 선택하고, sleepstudy 데이터셋을 찾아 선택한다.
sleepstudy 데이터셋이 활성화된다. R Commander 상단의 메뉴에서 < 활성 데이터셋 없음> 이 'sleepstudy'로 바뀐다.
summary(sleepstudy)
str(sleepstudy)'통계 > 요약 > 활성 데이터셋' 메뉴 기능을 통해서 sleepstudy 데이터의 요약 정보를 살펴보자. str() 함수를 이용하여 sleepstudy 데이터셋의 내부 구조를 살펴보자.
데이터셋의 내부는 다음과 같다:
| sleepstudy {lme4} | R Documentation |
Reaction times in a sleep deprivation study
Description
The average reaction time per day for subjects in a sleep deprivation study. On day 0 the subjects had their normal amount of sleep. Starting that night they were restricted to 3 hours of sleep per night. The observations represent the average reaction time on a series of tests given each day to each subject.
Format
A data frame with 180 observations on the following 3 variables.
Reaction
Average reaction time (ms)
Days
Number of days of sleep deprivation
Subject
Subject number on which the observation was made.
Details
These data are from the study described in Belenky et al. (2003), for the sleep-deprived group and for the first 10 days of the study, up to the recovery period.
References
Gregory Belenky, Nancy J. Wesensten, David R. Thorne, Maria L. Thomas, Helen C. Sing, Daniel P. Redmond, Michael B. Russo and Thomas J. Balkin (2003) Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose-response study. Journal of Sleep Research 12, 1–12.
Examples
str(sleepstudy)
require(lattice)
xyplot(Reaction ~ Days | Subject, sleepstudy, type = c("g","p","r"),
index = function(x,y) coef(lm(y ~ x))[1],
xlab = "Days of sleep deprivation",
ylab = "Average reaction time (ms)", aspect = "xy")
(fm1 <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy))
(fm2 <- lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject), sleepstudy))