Date post: | 11-Jan-2016 |
Category: |
Documents |
Upload: | patrick-warner |
View: | 216 times |
Download: | 0 times |
The purpose of this session
• To introduce the practice dataset (MUSP)
• To examine distributions
• To perform a preliminary analysis: know your data!
The MUSP CohortMater-University Study of Pregnancy
• 8556 pregnant women recruited at first antenatal visit 1981-1984 at the Mater Mother’s Hospital, Brisbane
• Follow-up of mother-child sets
The MUSP cohort
• Follow-ups (mother and child) at delivery + 3 days, 6 months, 5 years, 14 years, 21 years (ongoing)
• Current cohort of approximately 5000
• Some repeated pregnancies, multiple births
Information collected
• Socio-demographic information, health behaviour• Mental health, stressors, family functioning,
relationships• Biological data: pregnancy, delivery history• Physical, developmental assessment of child• Child behaviour • Health outcomes (mother and child)
Data structures
• Individual ID number (codea)
• Longitudinal record
codea a1 a2 a3…b1 b2 b3…c1 c2 c3….
• Restructure for ‘repeated measures’ analysis
Format:
codea a b c1 d1……. c2 d2……. c3 d3…….
1234 1 4 15.2 6….…. 16.6 9……. 18.6 11…….
Format:
codea time a b c d
1234 1 1 4 15.2 6 1234 2 1 4 16.6 91234 3 1 4 18.6 11
Longitudinal file
Stacked filerepeated measures
Time-dependent variables
Time-constant variables
Longitudinal file: mps.SinglePregnancyMother
Used for examining change over time within persons
Stacked file: mps.MentalHealth
Used for repeated measures analysis
Data Sets
The research questions
• Does mother’s mental health change over time?
• What factors (time-constant, time-dependent) predict mother’s mental health?
• What factors predict change in mother’s mental health?
Mother’s mental health
• 14 ordinal items on a five point scale: summed to make score 10 (good) – 50 (bad)
• Measured at six times so far:FCV, + 3 days, + 6 months, + 5 years,
+ 14 years, + 21 years
• Missing values and attrition
Possible predictors
• Age at First Clinic Visit
• Health status: time-dependent
• …………
Descriptive analysis
• Missing values and attrition
• Distribution
• Change over time
• Correlations over time
• Determinants of mental health
Descriptive analysis
• Missing values and attrition
Attrition and Missing Values
• Attrition high; include only those present at all phases FCV to +14 yearsN =4470
• Missing values elsewhere on particular items, comparatively infrequent.
Descriptive analysis
• Distribution (uses stacked file)
Descriptive analysis
• Change over time – grouped (uses stacked)
Variable Label N Mean Median Std Dev Minimum Maximum Skewness Kurtosis
amh bmh emh hmh kmh nmh
FCV + 3 days + 6 months + 5 years +14 years +21 years
4411 4463 4456 4455 4461 676
15.38 15.06 14.81 16.19 16.63 17.92
14.30 13.60 13.60 15.00 15.70 17.10
4.61 4.67 4.67 5.12 5.50 5.69
10.00 10.00 10.00 10.00 10.00 10.00
50.00 50.00 50.00 44.30 50.00 48.60
1.47 1.87 1.68 1.35 1.19 1.26
3.00 6.57 4.15 2.46 1.48 2.83
Variable Label N Mean Median Std Dev Minimum Maximum Skewness Kurtosis
lamh lbmh lemh lhmh lkmh lnmh
FCV + 3 days + 6 months + 5 years +14 years +21 years
4411 4463 4456 4455 4461 676
1.593 1.515 1.454 1.705 1.749 1.966
1.668 1.526 1.526 1.792 1.902 2.092
0.753 0.790 0.803 0.775 0.805 0.714
0.000 0.000 0.000 0.000 0.000 0.000
3.714 3.714 3.714 3.564 3.714 3.679
-0.278 -0.234 -0.072 -0.397 -0.419 -0.584
-0.465 -0.613 -0.778 -0.404 -0.474 0.047
Summary statistics for mental health score (high=poor)
Summary statistics for log(mental health score-9)
Poor Mental Health
GoodMental Health
Descriptive analysis
• Change over time – individual (uses longitudinal)
Poor Mental Health
GoodMental Health
Worsening
Improving
Poor Mental Health
GoodMental Health
Worsening
Improving
Descriptive analysis
• Correlations over time
Correlations for mental health score
Pearson Correlation Coefficients Number of Observations
FCV + 3 d + 6 m + 5 y +14y +21y
FCV 1.00000 4411
0.54331 4405
0.52288 4397
0.42221 4398
0.34201 4402
0.31288 665
+ 3 days 0.54331 4405
1.00000 4463
0.50318 4449
0.42270 4449
0.33176 4455
0.33231 674
+ 6 months 0.52288 4397
0.50318 4449
1.00000 4456
0.49279 4441
0.41533 4447
0.36792 675
+ 5 years 0.42221 4398
0.42270 4449
0.49279 4441
1.00000 4455
0.52577 4446
0.37132 673
+14 years 0.34201 4402
0.33176 4455
0.41533 4447
0.52577 4446
1.00000 4461
0.51146 676
+21 years 0.31288 665
0.33231 674
0.36792 675
0.37132 673
0.51146 676
1.00000 676
Correlations for log(mental health score-9)
Pearson Correlation Coefficients Number of Observations
FCV + 3 d + 6 m + 5 y +14y +21y
FCV 1.00000 4411
0.55385 4405
0.52858 4397
0.43313 4398
0.35467 4402
0.36037 665
+ 3 days 0.55385 4405
1.00000 4463
0.55643 4449
0.45615 4449
0.36176 4455
0.35962 674
+ 6 months 0.52858 4397
0.55643 4449
1.00000 4456
0.50648 4441
0.43387 4447
0.40551 675
+ 5 years 0.43313 4398
0.45615 4449
0.50648 4441
1.00000 4455
0.53554 4446
0.43299 673
+14 years 0.35467 4402
0.36176 4455
0.43387 4447
0.53554 4446
1.00000 4461
0.56196 676
+21 years 0.36037 665
0.35962 674
0.40551 675
0.43299 673
0.56196 676
1.00000 676
= 0.456 = 0.684
Descriptive analysis
• Determinants of mental health
Marital Status: a89 Frequency Percent Cumulative Frequency
Cumulative Percent
Missing 33 0.74 33 0.74
SINGLE 348 7.79 381 8.52
DE FACTO 374 8.37 755 16.89
MARRIED 3638 81.39 4393 98.28
SEPARATED-DIVORCED 70 1.57 4463 99.84
WIDOWED 6 0.13 4469 99.98
PARTNER IN PRISON 1 0.02 4470 100.00
Marital Status at FCV
Combine “Other”
Poor Mental Health
GoodMental Health
Means 2xSEM
Excluding “missing” and “other”Poor Mental Health
GoodMental Health
Single mothers poorer mental health at FCV, same at 6m, then widening gap
Poor Mental Health
GoodMental Health
Descriptive analysis
• Determinants of mental health (time-dependent)
Health Status at 5, 14 and 21 years
Table of HStatus by time
HStatus(Health Status) time
Frequency Col Pct
+ 5 years
+14 years
+21 years Total
Missing 6 0.13
7 0.16
1 0.15
14
Excellent 1061 23.74
993 22.21
76 11.23
2130
Good 2603 58.23
2445 54.70
291 42.98
5339
Fair 687 15.37
872 19.51
234 34.56
1793
Poor 113 2.53
153 3.42
60 8.86
326
Very Poor 0 0.00
0 0.00
15 2.22
15
Total 4470 4470 677 9617
Frequency Missing = 3793
Better physical health, better mental health, at all times
Poor Mental Health
GoodMental Health
Physical Health
Better physical health, better mental health, at all times, association stronger at 14 years
Poor Mental Health
GoodMental Health
Physical HealthTime
Poor Mental Health
GoodMental Health
Time
Poor Physical Health
Excellent Physical Health
The MUSP dataset
• The subset available for all phases to 21 years (N = 667)in a ‘stacked’ file: MentalHealth
• Outcome: Logged maternal mental health score
• Time-constant variables: At FCV: Marital status, Income, Education, Age group, Number of previous pregnancies, Country of birth, Time in Australia
• Time-dependent variables: Physical health status