Descriptive Statistics Mean login to view 2 more bullets Median login to view 5 more bullets Mode login to view 3 more bullets Types of Distributions Normal login to view 3 more bullets Bi-modal login to view 2 more bullets Skewed login to view 9 more bullets Other login to view 2 more bullets Characteristics of the Normal Distribution For continuous variables Defined entirely by 2 parameters Mean (µ) login to view 1 more bullet A certain percentage of all observations will always fall within +/- certain standard deviations of the mean login to view 3 more bullets Regression to the Mean Phenomenon in which sample points which were initially extreme often become closer to the mean in future measurements Most points will fall near on the average; therefore, extreme points are often a result of "luck" (e.g., a student performs particularly poor on an exam but normally performs at the average level) Has significance for study design login to view 2 more bullets Measures of Variability Standard deviation login to view 5 more bullets Standard error login to view 4 more bullets