1/15/2020

Discussion of Grid for NCAA Championship

• Duing our first class, you agreed that all 10 digits were not equally likely to occur at the end of each quarter. Explain how you obtained data to support your conclusion. What statistical methods and graphical displays did you use to support your rationale?

Types of Variables

• A quantitative variable is a variable that takes on numerical values for which arithmetic makes sense.
• A categorical or qualitative variable is a variable that records which category a person place or thing falls into.

Questions about data

• What variables are being measured?
• Are these variables appropriate for answering the question(s) of interest?
• What are the units of measurement?
• How are the data recorded?

Graphical Displays

• Why are graphing techniques useful?
  • Examine the overall shape of a distribution - (symmetric or skewed?)
  • Look for deviations from the overall shape - (unusual observations, gaps, etc.)
  • Locate the center of the distribution

Stem and Leaf Plots

• Separate each observation into a stem and a leaf.
• List the stems vertically in increasing order from top to bottom.
• Add the leaves (typically the last digit) to the right of the stems.

Histograms

• Divide the range of the data into classes of equal width.
• Count the number of observations in each class.
• Compute the relative frequency or percent for each class.
• Erect bars over each class interval.

Graphical Displays with R (Open p:\data\math\hartlaub\SportsStats\ReactionTimeS2018.csv)

• Your first R script - Open ReactionTime.R
• Stemplots - stem(x)
• Histograms - hist(x)
• Dotplots - dotchart(x)
• Bar Charts - barplot(counts)
• Pie Charts - pie(counts)

Comments and Questions on Chapter 1 Reading

Introduction to Simulation

• SRIS web site
• Statkey
• We will learn how to do simulation with R next week.

Class exercises - Getting comfortable with R

• Compare (graphically and numerically) the reaction times and pulses of women and men.
• Compare (graphically and numerically) the reaction times and pulses of different classes. (Use the data from 2016 for this question.)
• Is the class in good shape? Create a variable and descriptive statistics to address this question.
• Replicate the simulation methods used in the examples for Chapter 1. Are your results exactly the same? Are your conclusions the same?

Reading Assignment - Please complete your reading of Chapter 1 for class on Friday and begin reading Chapter 2.