A dataset with developmental scores at the item level for 2139 unique children measured in the years 1991-1996 at ages clustered around six months (n = 128), 12 months (n = 1732) and 18 month (n = 279).



A data.frame with 2139 rows and 113 variables:

ctrcdchrCountry code (ISO 3166-1 alpha-3)
cohortchrCohort name
cohortnchrCohort number
subjidintChild number
agedaysintAge (days)
sexchrEither "male" or "female"
gagebrthintGestational age (days)
by1mdd0450/1inspects own hand
by1mdd0460/1Closes on dangling ring (check hand preference)
by1mdd0470/1turns head to sound of bell
by1mdd0480/1turns head to sound of rattle
by1mdd0490/1reaches for cube
by1mdd0500/1manipulates table edge actively
by1mdd0510/1eye-hand coordination in reaching
by1mdd0520/1regards pellet
by1mdd0530/1mirror image approach
by1mdd0540/1picks up cube (check hand preference)
by1mdd0550/1Vocalises attitudes
by1mdd0560/1retains 2 cubes
by1mdd0570/1exploitive paper play
by1mdd0580/1Discriminates strangers
by1mdd0590/1recovers rattle, in crib
by1mdd0600/1reaches persistently
by1mdd0610/1Likes frolic play
by1mdd0620/1turns head after fallen spoon
by1mdd0630/1lifts inverted cup
by1mdd0640/1reaches for second cube
by1mdd0650/1smiles at mirror (5.4 months)
by1mdd0660/1bangs in play
by1mdd0670/1sustained inspection of ring
by1mdd0680/1exploitive string play
by1mdd0690/1transfers objects hand to hand
by1mdd0700/1picks up cube deftly and directly
by1mdd0710/1pulls string: secures ring
by1mdd0720/1interest in sound production
by1mdd0730/1lifts cup with handle
by1mdd0740/1attends to scribbling
by1mdd0750/1looks for fallen spoon
by1mdd0760/1playful response to mirror
by1mdd0770/1retains 2 of 3 cubes offered
by1mdd0780/1manipulates bell: insterest in details
by1mdd0790/1vocalizes 4 different syllables
by1mdd0800/1pulls string adaptively: secures ring
by1mdd0810/1cooperates in games (is this some other scale?)
by1mdd0820/1attempts to secure 3 cubes
by1mdd0830/1rings bell purposely
by1mdd0840/1listens selectively with familiar words
by1mdd0850/1says "da-da" or equivalent
by1mdd0860/1Uncovers toy (check manual if by pulling cloth
by1mdd0870/1fingers holes in pegboard
by1mdd0880/1picks up cup, secures cube
by1mdd0890/1responds to verbal request
by1mdd0900/1puts cube in cup on command
by1mdd0910/1looks for content of box
by1mdd0920/1stirs with spoon in imitation
by1mdd0930/1looks at pictures in book
by1mdd0940/1inhibits on command
by1mdd0950/1attempting to imitate scribble
by1mdd0960/1unwraps cube
by1mdd0970/1repeats performance laughed at
by1mdd0980/1holds crayon adaptively
by1mdd0990/1pushes car along
by1mdd1000/1puts 3 or more cubes in cup
by1mdd1010/1jabbers expressively
by1mdd1020/1uncovers blue box
by1mdd1030/1turns pages of books
by1mdd1040/1Pats toy (whistle doll) in imitation
by1mdd1050/1dangles ring by string
by1mdd1060/1imitates words
by1mdd1070/1puts beads in box (6 of 8)
by1mdd1080/1places 1 peg repeateadly
by1mdd1090/1removes pellet from bottle
by1mdd1100/1blue board: places 1 round block
by1mdd1110/1builds tower of 2 cubes
by1mdd1120/1scribbles sponstaneously
by1mdd1130/1says 2 words
by1mdd1140/1puts 9 cubes in cup
by1mdd1150/1closes round box
by1mdd1160/1uses gestures to make wants known
by1mdd1170/1shows shoes or other clothing, or own toy
by1mdd1180/1pegs placed in 70 seconds
by1mdd1190/1builds tower of 3 cubes
by1mdd1200/1pink board: places round block
by1mdd1210/1blue board: places 2 round blocks
by1mdd1220/1attains toy with stick
by1mdd1230/1pegs placed in 42 seconds
by1mdd1240/1names 1 object
by1mdd1250/1imitates crayon stroke
by1mdd1260/1follows directions doll (check parts passed)
by1mdd1270/1uses words to make wants known
by1mdd1280/1points to parts of doll (check parts recognised, check manua
by1mdd1290/1blue board: places 2 round and 2 square blocks
by1mdd1300/1names 1 picture
by1mdd1310/1finds 2 objects
by1mdd1320/1points to 3 pictures
by1mdd1330/1No label: b1m133
by1mdd1340/1pegs placed in 30 seconds
by1mdd1350/1differentiates scribble from stroke
by1mdd1360/1sentence of 2 words
by1mdd1370/1pink board: completes
by1mdd1380/1names 2 objects
by1mdd1390/1points to 5 pictures
by1mdd1400/1broken doll: mends approximately
by1mdd1410/1names 3 pictures
by1mdd1420/1blue board: places 6 blocks
by1mdd1430/1builds tower of 6 cubes
by1mdd1440/1discriminates 2: cup, plate, box
by1mdd1450/1names watch, 4th picture
by1mdd1460/1names 3 objects
by1mdd1500/1names watch, 2nd picture
by1mdd1510/1pink board: reverse
by1mdd1520/1discriminates 3: cup, plate, box
by1mdd1530/1broken doll: mends exactly


Instruments: Bayley I (by1)


Lozoff B, De Andraca I, Castillo M, Smith JB, Walter T, Pino P. Behavioral and developmental effects of preventing iron-deficiency anemia in healthy full-term infants. Pediatrics. 2003;112:846-854. https://pediatrics.aappublications.org/content/112/4/846.short