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Showing posts with the label Biostatistics

2 x 2 Contingency Table Calculations and Formulas

Positive predictive value = TP/ (TP + FP) Negative predictive value = TN/ (TN + FN) Sensitivity = TP / (TP + FN) Specificity = TN/ (TN + FP)

Confounding bias

When there is a confounding factor (something that is associated with both the exposure and outcome).

When there are problems with the collection of information e.g. errors in measurement of exposure and outcome. To minimize, standardization of measurement techniques and training of observers is needed

Sample Distortion Bias

When the sample population differs from the target population with respect to their exposure and/ or the outcome.

Hawthorne Effect

When the people/ subjects in the study are aware that they are being studied they will behave differently and therefore affect the outcome of the study. To minimize this bias, the subjects must not be aware that they are being studied.