Matched samples, I've learnt, alongside random assignment are the key to a robust comparative research design. Gertler and colleagues (2014) longitudinal study was informative of covariates that can radically impact on learning outcomes. Below is an assignment from my post-grad studies, the headings are from the rubric as we were not assigned any specific risk of bias assessment tool.
Research Questions
• Not clearly stated; cross-referenced with an earlier publication about the study, Gertler et al. (2013)
• Can high quality maternal child modeling improve parental investment and subsequent labour returns for the community?
• Does early childhood-development have greater impact in developing countries (compared to developed nations) because of lower stimulation at home prior to an intervention?
• What are the impacts of toddler psychosocial stimulation on young adult earnings?
• Will stimulation enable a stunted treatment group to catch up with a non stunted comparison group and compensate for psychological delays?
Population of Interest
• Non stunted comparison group
Population of the Study
• Growth stunted children living in poverty with their mothers in Kingston, Jamaica 1986-1987
Population of Inference
• Apx. 200 million children under the age of 5 living in developing countries at risk of not reaching their full potential as citizens
Intervention Conditions
Toddlers (1986
1987)
•
Children aged between 9 and 24 months
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Intervention groups were children stunted in their growth (> 2 SD
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Stratified by age and gender
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Random assignment to one of 4 conditions:
psychosocial stimulation (n = 32)
psychosocial and nutrition (n = 32)
nutrition (n = 32)
control (n = 33)
NB. Nutritional supplement had no significant effect
pooled groups
Treatment group = psychosocial + psychosocial and nutritional groups (n = 64)
Control group = nutrition + control groups (n = 65)
Tested for robustness
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Plus 1 non stunted comparison group (n = 84)
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•‘Sensible’ sample number in that at least 30 in each group (Tabachnick &
Fidel, 2013)
References