Case Study: Lead Exposure in Children

Case Study: Lead Exposure in Children

 

Objective
The aim of this Case Study
is to pull together what have
been covered in the course to date.
Emphasis is placed on material covered in module 03. This work is based on an
actual
paper
(available in
D2L
à
Module 05
à
R
eading folder)
by Landrigan et al. (1975) “Neuropsychological
dysfunction in children with chronic low

level lead absorption”, The Lancet, Ma
rch, 29, pp. 708

712.
However the data is fictitious.
Because the data is
fabricated your results may not match those
reported in the paper
by Landrigan et al
.
This project will help
you acquire
most of the statistical tools
necessary for the descriptive section
of
a published
manuscript
.
Procedures
Before
attempting this work
,
please
read the paper by Landrigan et al. (1975)
available in Module 05
à
Reading folder.
Though
this paper was
published in 1975, it still has an impact today. The topic of
lead exposure in children remains
under investigation
.
As such another paper to
read during the
course of this project is the recent work by Dr.
Mona Hanna

Attisha
et al. on
Elevated Blood Lead
Levels in Children Associated
With Drinking Water
in
Flint
Michigan. This paper is also available in
D2L
à
Module 05
à
Reading folder
.
Data
set
for
this project
(LeadHM802)
is located in the
HM802
library in SAS
. A description of all the
variables names in
the data set (often called a Code Book) can be found at the end of this
document
.
Questions
1.
The main analysis in the paper compares the mean performance IQ scores for children
with high lead levels and children with low lead levels.
a.
Provide the 5

point summary for the performance IQ score variable.
b.
Graphically display and describe the distributi
ons of performance IQ scores of the
lead absorption group and control group.
c.
Describe any differences between the two groups’ distributions of performance IQ.
Offer a few sentences to address the following items
à
compare the location of most
of the data, t
he spreads of the distributions, and whether there are outliers.
2.
As best as you can p
lease r
e

create Tables
1,
2
and 3
in the paper.
D
escribe the results.
Note, you are not required to test for statistical significance.
Also, some variables may be
missing for example the variable for “No. speaking some or all Spanish at home” is missing.
You are not required to reproduce results for this variable.
3.
Please stay

t
uned for
this question
, which will be based on
Cross

Tabulated Counts
(Ch.18) calculating Odds Ratios.
Code Book

A description of all the variables names in the data
set.
VARIABLE COLUMN DESCRIPTION
id 1

3 IDENTIFICATION NUMBER
area 5 AREA

RESIDENCE ON AUG’72
1=0

1 MILES FROM SMELTER
2=1

2.5 MILES
3=2.5

4.1 MILES
ag
eyrs 7

11 AGE in years xx.xx
Age_distribution
Age Distribution
sex 13 SEX 1=MALE 2=FEMALE
IQ TEST RESULTS
iqv_inf 15

16 INF

INFORMATION SUBTEST IN WISC AND WPPSI
iqv_comp
18

19 COMP

COMPREHENSION SUBTEST IN WISC AND WPPSI
iqv_ar 21

22 AR

ARITHMETIC SUBTEST IN WISC AND WPPSI
iqv_ds 24

25 DS

DIGIT SPAN SUBTEST(WISC) AND SENTENCE
COMPLETION(WPPSI)
iqv_raw 27

28
V/RAW

RAW SCORE/VERBAL IQ
iqp_pc 30

31 PC

PICTURE COMPLETION SUBTEST IN WISC AND WPPSI
iqp_bd 33

34 BD

BLOCK DESIGN SUBTEST IN WISC AND WPPSI
iqp_oa 36

37 OA

OBJECT ASSEMBLY SUBTEST(WISC), ANIMAL HOUSE
SUBTEST(WPPSI)
iqp_cod 39

40 COD

CODING SUBTEST(WISC), GEOMETRIC DESIGN
SUBTEST(WPPSI)
iqp_raw 42

43 P/RAW

RAW SCORE/PERFORMANCE IQ (TOTAL OF SCORES
PC, BD, OA,
& COD)
hh_index 45

46 HH/INDEX

HOLLINGSHEAD INDEX OF SOCIAL STATUS
iqv 48

50 IQV

VERBAL IQ
iqp 52

54
IQP

PERFORMANCE IQ
iqf 56

58 IQF

FULL SCALE
IQ (NOT SUM OR AVERAGE OF IQV D
IQP)
iq_type
60 TYPE OF IQ TEST
1=WISC 2=WPPSI(WISC USUALLY GIVEN
TO CHILDREN GE 5 YRS 1 MONTH OF AGE
WPPSI USUALLY
GIVEN TO CHILDREN LE 5YRS OF AGE)
lead_grp 62 GROUP

BLOOD LEAD LEVEL GROUP
1
=BLOOD LEAD LEVELS BELOW 40 MICROGRAMS/100ML IN
BOTH 1972 & 1973
(control group)
2=BLOOD LEAD LEVELS GREATER THAN OR EQUAL TO
40
MICROGRAMS/100ML
IN BOTH 72 & 73 OR A LEVEL GREATER
THAN OR
EQUAL TO 40
IN 73 ALONE (3 CASES ON
LY)
(currently exposed Group)
3=BLOOD LEAD LEVELS GREATER THAN OR EQUAL TO
40 MICROGRAMS/100ML
IN 72 AND LESS THAN 40 IN 73
(previously exposed group)
Group 64
1=control group; 2=exposed group
ld72 66

67 LD72

BLOOD LEAD VALUES (MICROGRAMS/100ML) IN72
MISSING=99
ld73 69

70 LD73

BLOOD LEAD VALUES (MICROGRAMS/100ML) IN 73
fst2yrs 72 FST2YRS

DID
CHILD LIVE FOR 1ST 2 YRS WITHIN
1 MILE OF SMELTER
1=YES 2=NO
totyrs 74

75 TOTYRS

TOTAL NUMBER OF YEARS SPENT WITHIN
4.1 MILES OF SMELTER
SYMPTOM DATA (AS REPORTED BY PARENTS
)
pica 77 PICA 1=YES 2=NO
colic 79 COLIC 1=YES 2=NO
clumsi 81 CLUMSINESS 1=YES 2=NO
irrit 83 IRRITABILITY 1=YES 2=NO
convul 85 CONVULSIONS 1=YES 2=NO
CONTAIN
NEUROLOGICAL TEST DATA
_2plat_r 87

88 # OF TAPS FOR RIGHT HAND IN THE 2

PLATE TAPPING
TEST (#TAPS IN ONE 10 SECOND TRIAL)
MISSING=99
_2plat_l 90

91 # OF TAPS FOR LEFT HA
ND IN THE 2

PLATE TAPPING TEST
(#TAPS IN ONE 10 SECOND TRIAL)
MISSING=99
visrea_r 93

94 VISUAL REACTION TIME RIGHT HAND (MILLISECONDS)
MISSING=99
visrea_
l 96

97 VISUAL REATION TIME LEFT HAND (MILLISECONDS)
MISSING=99
audrea_r 99

100 AUDITORY REACTION TIME RIGHT HAND (MILLISECONDS)
MISSING=99
audrea_l 102

103 AUDITORY REACTION
TIME LEFT HAND (MILLISECONDS)
MISSING=99
fwt_r 105

106 FINGER

WRIST TAPPING TEST RIGHT HAND
(# TAPS IN ONE 10 SECOND TRIAL)
MISSING=99
fwt_l
108

109 FINGER

WRIST TAPPING TEST LEFT HAND
(#TAPS IN ONE 10 SECOND TRIAL)
MISSING=99
hyperact 111

112 WWPS

WERRY

WEISS

PETERS SCALE FOR HYPERACTIVITY
0=NO ACTIVITY . . . . 4=SEVERLY HYPERACTIVE
(AS REPORTED BY PARENTS)
MISSING=99
maxfwt 114

115 Finger

wrist tapping test in dominant hand(max of
fwt_r,fwt_l)

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