Normal distribution Non-normal distribution a. Positive skew: Longer or fatter tail on right b. Negative skew: Longer or fatter tail on left 2X2 tables Disease present Disease absent Test positive TP FP Test negative FN TN Event Non-event Exposed or Treatment a b Non-exposed or Placebo c d Formulae Incidence…
Tag: Biostatistics
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Which statistical test to use?
Steps: Types of data Mnemonic: NOIR Qualitative or Categorical data a. Nominal (relating to name): Groups e.g. gender (male/female), color (black/white), blood groups (A/B/AB/O), religions (hindu/muslim/christian) b. Ordinal (relating to order): Rank-ordered data but without meaningful difference; e.g. socio-economic status (low, middle and high), rank (1st, 2nd and 3rd)– without…