MedicalStat

Formulas


Note: In the formulas the symbol \( \ln(x) \) is the natural logarithm. In other words the inverse function of \( \text{e}^x = \exp(x) \) meaning that \( \ln(\text{e}^x) = x \) and that \( \text{e}^{\ln(x)} = x \). In some text books, \( \ln(x) \) is written as \( \log(x)\). The expression \( \log(x) \) is, however, normally attributed to the base-10-logarithm, not the natural logarithm.

The symbol \( |x| \) is the numerical value of a number. The numerical value is always positive. For ex. \( |3-5| = |-2| = 2 \) and \( |5-3| = |2| = 2 \).


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Risk and Odds


Sensitivity & Specificity



Means



Confidence Intervals


Chi-Square-Test



Weighted Average


Data Analysis



Rates



Mantel-Haenszel Stratified OR



Mann-Whitney (Wilcoxon) U Test



Regression



Power & Sample Size