STP 231 Study Guide - Midterm Guide: Frequency Distribution, Descriptive Statistics, Linear Map
Document Summary
Identify the experimental units, treatments, blinding (if applicable), placebo effect (if applicable) Know how to read a random numbers table. To confirm cluster, check if all subjects from selected groups are included in the sample. Yes, then ask: are all groups represented in the sample. Frequency distribution/relative frequency distribution for numeric and categorical variables. For numeric variable: dotplot, stem-and-leaf, histogram, and boxplot. Determine the shape of a distribution from a graphical display: Measure of center: mean, median, and mode. N is the number of observations taken (different data values) Determine the shape based on mean and median. Outlier cannot simply be removed unless there was a mistake in recording. Measure of spread: find the range and standard deviation. Range = maximum value - minimum value. Empirical rule: for any sample of observations with a symmetric and unimodal distribution, we expect to find: 68% of all values fall within the interval (x-bar - s, x-bar + s)
