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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.
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Mother and Child Health: Research Methods G.J.Ebrahim Editor Journal of Tropical Pediatrics, Oxford University Press.
The Normal Distribution • A histogram provides a view of how the values of a variable are distributed.
Number of values and the Gausian shape • All these histograms illustrate a Normal distribution. As the number increases the Gausian shape becomes more obvious
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.
Outliers • An outlier is an unusually high value of Y for a given value of X. Outliers exert an influence on the regression line.
Rates, Proportions and Ratios MEASURE: Rate Proportion Ratio EXAMPLE: Incidence Prevalence Maternal Mortality Rate Rate ratio
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