[R] nlme: fewer observations than random effects in all level 1 groups

John Sorkin jsorkin at grecc.umaryland.edu
Thu Aug 25 16:48:42 CEST 2016


I am getting a warning message when I run lme:
 
Warning message:
In lme.formula(fixed = value ~ CorT + time + CorT * time, data = GD) :
  fewer observations than random effects in all level 1 groups
I don't know what the message means, nor if I need to be concerned about the message. I would be
grateful if someone could explain the message to me, and tell me if I need to have concern.
My data and code follows. You should be able to copy, paste and run the code. (n.b. you will need nlme).
Thank you,
John

library(nlme)
data10 <- structure(list(SS = c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 
                      11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L, 19L, 20L, 21L, 22L, 23L, 
                      24L, 25L, 26L, 27L, 28L, 29L, 30L, 31L, 32L, 33L, 34L, 35L, 36L, 
                      37L, 38L, 39L, 40L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 
                      11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L, 19L, 20L, 21L, 22L, 23L, 
                      24L, 25L, 26L, 27L, 28L, 29L, 30L, 31L, 32L, 33L, 34L, 35L, 36L, 
                      37L, 38L, 39L, 40L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 
                      11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L, 19L, 20L, 21L, 22L, 23L, 
                      24L, 25L, 26L, 27L, 28L, 29L, 30L, 31L, 32L, 33L, 34L, 35L, 36L, 
                      37L, 38L, 39L, 40L), 
                      group = structure(c(1L, 1L, 1L, 1L, 1L, 
                      1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
                      2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
                      2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
                      1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
                      2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 
                      1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
                      2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
                      2L, 2L, 2L), .Label = c("Cont", "Inte"), class = "factor"), 
                      time = c(0L,0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
                      0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
                      0L, 0L, 0L, 0L, 0L, 0L, 0L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
                      3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
                      3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 6L, 
                      6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 
                      6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 
                      6L, 6L, 6L, 6L, 6L, 6L, 6L),
                      value = c(2, 1, 3, 6, 1, 5, 4, 4, 
                      3, 4, 5, 8, 4, 4, 0, 10, 3, 0, 4, 6, 7.86633577663451, 14.8276520497166, 
                      5.82301333779469, 6.28030818421394, 7.63550981180742, 7.12941627483815, 
                      14.4640282960609, 8.45473791006953, 9.05422623036429, 10.3654135158285, 
                      7.75828687706962, 9.05671408865601, 9.35509188333526, 8.22054158896208, 
                      5.03435689257458, 14.7296907380223, 6.12912589916959, 10.4857219522819, 
                      13.7229738035239, 13.6259456002153, 7.28073637914354, 5.54352982843898, 
                      8.01713229269774, 13.2061931600758, 3.76887153466896, 10.7523541087606, 
                      9.6018583095559, 9.62481826991277, 8.90923221009558, 8.85276119502607, 
                      10.9778885179292, 13.4521386035968, 9.95012926745246, 7.78767098907235, 
                      5.47606805783807, 16.266090481022, 8.10664718517709, 3.98960108796381, 
                      10.1788924241439, 9.16177207287154, 11.6541174116198, 19.055363149052, 
                      10.4729343696394, 12.9615216852694, 10.3448541992752, 12.1246619594601, 
                      17.9078516870675, 14.1546013378432, 14.3556335566072, 13.7020998307993, 
                      12.2669613611438, 13.6968944583291, 16.0242423205925, 14.1618907899469, 
                      11.6571628686932, 20.6208065318508, 10.5981108892906, 16.506205140693, 
                      19.8382587955876, 18.8215423103255, 13.6293066791555, 10.679427547606, 
                      14.5715854764237, 18.0672964438053, 8.64819129644325, 16.5046323205086, 
                      14.933146372713, 13.0224731390702, 13.1364074268251, 12.7299140722498, 
                      16.3687231173825, 17.3307585790136, 14.8835947338426, 13.7832964561028, 
                      8.18806783970065, 20.4643754783345, 13.927444172043, 7.95214003187942, 
                      15.8500600646401, 14.863828811346, 16.3418851303983, 23.9363727442689, 
                      15.6973592017088, 16.8376901116903, 16.4265975193717, 18.3862045830691, 
                      23.7260777608949, 19.6736595029528, 18.7411384574001, 21.5299075269243, 
                      18.7672717818268, 18.6586905356669, 20.1908194122778, 19.6037057845507, 
                      16.2952035024787, 25.2275624425201, 15.7628539929276, 21.2326533842687, 
                      25.3146615100186, 24.5526929132951), 
                      baseline = c(2, 1, 3, 6, 
                      1, 5, 4, 4, 3, 4, 5, 8, 4, 4, 0, 10, 3, 0, 4, 6, 7.86633577663451, 
                      14.8276520497166, 5.82301333779469, 6.28030818421394, 7.63550981180742, 
                      7.12941627483815, 14.4640282960609, 8.45473791006953, 9.05422623036429, 
                      10.3654135158285, 7.75828687706962, 9.05671408865601, 9.35509188333526, 
                      8.22054158896208, 5.03435689257458, 14.7296907380223, 6.12912589916959, 
                      10.4857219522819, 13.7229738035239, 13.6259456002153, 2, 1, 3, 
                      6, 1, 5, 4, 4, 3, 4, 5, 8, 4, 4, 0, 10, 3, 0, 4, 6, 7.86633577663451, 
                      14.8276520497166, 5.82301333779469, 6.28030818421394, 7.63550981180742, 
                      7.12941627483815, 14.4640282960609, 8.45473791006953, 9.05422623036429, 
                      10.3654135158285, 7.75828687706962, 9.05671408865601, 9.35509188333526, 
                      8.22054158896208, 5.03435689257458, 14.7296907380223, 6.12912589916959, 
                      10.4857219522819, 13.7229738035239, 13.6259456002153, 2, 1, 3, 
                      6, 1, 5, 4, 4, 3, 4, 5, 8, 4, 4, 0, 10, 3, 0, 4, 6, 7.86633577663451, 
                      14.8276520497166, 5.82301333779469, 6.28030818421394, 7.63550981180742, 
                      7.12941627483815, 14.4640282960609, 8.45473791006953, 9.05422623036429, 
                      10.3654135158285, 7.75828687706962, 9.05671408865601, 9.35509188333526, 
                      8.22054158896208, 5.03435689257458, 14.7296907380223, 6.12912589916959, 
                      10.4857219522819, 13.7229738035239, 13.6259456002153), 
                      CorT = c(0, 
                      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 
                      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 
                      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 
                      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 
                      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 
                      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)), 
                      row.names = c(NA, 
                      -120L), .Names = c("SS", "group", "time", "value", "baseline", 
                      "CorT"), class = "data.frame")
data10

GD2<- groupedData(value~time+CorT+time*CorT|SS,data=data10,FUN=mean)
fit1 <- lme(GD2)
summary(fit1)
John David Sorkin M.D., Ph.D.
Professor of Medicine
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing) 

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