Descriptive vs. Inferential Two branches of Statistics 11/20/2018

from Bluman 5th Ed. textbook (c) McGraw-Hill 1-1 Descriptive and Inferential Statistics (Bluman, 5th ed. © McGraw-Hill) Descriptive statistics consists of the collection, organization, summarization, and presentation of data. Inferential statistics consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. 11/20/2018 from Bluman 5th Ed. textbook (c) McGraw-Hill

From “Beginning Statistics” by Warren, Denley, Atchley, pages 7-8 “Two main branches” Descriptive Statistics: gathers, sorts, summarizes, and presents…. Raw data, graphs, tables, numerical summaries, etc. Inferential Statistics: deals with the interpretation of the information collected, typically conclusions about some hypothesis, estimating population parameters. (© 2008 Hawkes Learning Systems/Quant Systems) 11/20/2018

A Point of Transition The early part of Math 2205 is about Descriptive Statistics, frequency distributions, probability distributions, graphs and charts. The later part of Math 2205 turns to Inferential Statistics Confidence intervals Hypothesis testing Correlation, Regression, and making predictions 11/20/2018

Examples Descriptive Statistics Inferential Statistics We measured the heart rate of each student in Mrs. Green’s PHED 1182 Walking class and the mean was _____ beats per minute, the standard deviation was _____, and the minimum was _____ and the maximum was _____. We measured the heart rate of each student in Mrs. Green’s PHED 1182 Walking class and then announced that we are 95% confident that the mean heart rate of students who walk regularly is between ______ and _____ beats per minute. 11/20/2018

Examples Descriptive Statistics Inferential Statistics We obtained the Placement Test results from Traci’s office and computed the mean scores in the English test. We also make some pretty pictures like the ones in Chapter 2 – histograms, frequency polygons, and ogives, too. We obtained the Placement Test results from the main campus, too. We performed a hypothesis test to determine the truth of the conjecture “Applicants at the Cordele campus have statistically significant higher scores than main campus applicants.” 11/20/2018

Examples Descriptive Statistics Inferential Statistics We obtained the placement test scores of 100 applicants who were admitted to Darton State College. We tracked these students and found the total number of college credits earned. We constructed a y = mx + b linear model to correlate y = credits earned based on x = placement test score. And we used that model to make predictions of success for new applications. 11/20/2018