mother and child health: research methods
DESCRIPTION
Mother and Child Health: Research Methods. G.J.Ebrahim Editor Journal of Tropical Pediatrics, Oxford University Press. Programmes Menu of Epi-Info. The Normal Distribution. A histogram provides a view of how the values of a variable are distributed. Number of values and the Gausian shape. - PowerPoint PPT PresentationTRANSCRIPT
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Mother and Child Health: Research Methods
G.J.Ebrahim
Editor
Journal of Tropical Pediatrics, Oxford University Press.
![Page 2: Mother and Child Health: Research Methods](https://reader035.vdocument.in/reader035/viewer/2022062321/5681324e550346895d98c700/html5/thumbnails/2.jpg)
Programmes Menu of Epi-Info
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The Normal Distribution
• A histogram provides a view of how the values of a variable are distributed.
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Number of values and the Gausian shape
• All these histograms illustrate a Normal distribution. As the number increases the Gausian shape becomes more obvious
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Scatterplot to show relationship between two numeric variables
• A scatterplot of dose of anaesthetic and time to recover from anaesthesia, with a regression line and 95% confidence intervals as well as outliers.
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Outliers
• An outlier is an unusually high value of Y for a given value of X. Outliers exert an influence on the regression line.
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Rates, Proportions and Ratios
Is numerator included in the denominator?
Yes No
Is time included in denominator?
Yes No
MEASURE: Rate Proportion Ratio
EXAMPLE: Incidence Prevalence Maternal Mortality
Rate Rate ratio
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Absolute risk, Probability of survival and Odds ratio
Absolute Risk Survival Probability
Odds
0.90 1−0.90 = 0.10 0.90÷(1−0.9) =9.0
0.75 1−0.75 = 0.25 0.75÷(1−0.75) = 3.0
0.50 1−0.50=0.50 0.50÷(1−0.50)=1.0
0.25 1−0.25=0.75 0.25÷(1−0.25)=0.33
0.10 1−0.10=0.90 0.10÷(1−0.10)=0.11
0.01 1−0.01=0.99 0.01÷(1−0.01)=0.01
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Calculating Numbers Needed to Treat (NNT)
• Calculate the proportion of people who have the outcome in the intervention group. (Exp.Grp.Evnt Rate; EGER )
• Calculate the proportion of people who have the outcome in the control (placebo) group. (Cntrl. Grp.Event Rate; CGER)
• Calculate the difference between EGER and CGER to obtain Absolute Risk Reduction (ARR)
• Then NNT = 1÷ARR