STAT1201 - Lecture 2.1, week 2 2.1 - Exploratory Data Analysis p1 All Rstudio work completed in Rstudio* Histograms and Density Plots - Most useful and common graphs for displaying continuous data - Histograms represent the frequency distribution of continuous data with no gaps between bars Graphical representation tells you key features of data such as shape and spread. For a complete understanding of the data, you need numerical summaries. Central tendency and Location - provides information about the centre or middle of a quantitative variable. - Mode - most frequently occurring value - Medium - The middle value in the ordered data - Mean - average in a set of numbers M = Measures of location - Percentiles and quartiles are measures of location - Percentiles divide a set of ranked data so that a certain fraction of data is falling on or below this location e.g., 10th percentile is the value such that 10% of the data are equal to or below that value - Quartiles are labelled between the values 0 - 1 e.g., 0.1 = 10th percentile - Divide a set of ranked data into four subgroups or parts denoted by Q1, Q2 and Q3 - Q1 = first 25% of data or 0.25 - Q2 = first 50% of data or 0.5 - Q3 = first 75% of data or 0.75 R is used to find Q1, Q2 and Q3