Chapter 3 Lesson 3.1 Graphical Methods for Describing Data 3.1: Displaying Categorical Data

Segmented Bar Charts When to UseCategorical data How to construct – MUST first calculate relative frequencies – Draw a bar representing 100% of the group – Divide the bar into segments corresponding to the relative frequencies of the categories

Relative Frequency Ideal DistanceStudentsParents Less than 250 miles to 500 miles to 1000 miles More than 1000 miles The Princeton survey... Create a segmented bar graph with these data. First draw a bar that represents 100% of the students who answered the survey.

Less than 250 miles 250 to 500 miles 500 to 1000 miles More than 1000 miles Relative Frequency Ideal DistanceStudentsParents Less than 250 miles to 500 miles to 1000 miles More than 1000 miles First draw a bar that represents 100% of the students who answered the survey. Relative frequency Students Next, divide the bar into segments. Do the same thing for parents – don ’ t forget a key denoting each category Parents

Pie Chart When to Use Categorical data How to construct –Draw a circle to represent the entire data set –Calculate the size of each “slice”: Relative frequency × 360° –Using a protractor, mark off each slice To describe – comment on which category had the largest proportion or smallest proportion

Typos on a résumé do not make a very good impression when applying for a job. Senior executives were asked how many typos in a résumé would make them not consider a job candidate. The resulting data are summarized in the table below. Number of TyposFrequencyRelative Frequency or more10.07 Don ’ t know5.03 Create a pie chart for these data.

Number of TyposFrequencyRelative Frequency or more10.07 Don ’ t know5.03 First draw a circle to represent the entire data set. Next, calculate the size of the slice for “ 1 typo ”.40×360º =144º Draw that slice. Repeat for each slice. Here is the completed pie chart. What does this pie chart tell us about the number of typos occurring in résumés before the applicant would not be considered for a job?

Pie ChartSegmented Bar Graph

Class Survey Using the class survey on “What school activity are you most involved in outside of class?” create the following…. 1) Pie Chart comparing gender 2) Segmented Bar Chart comparing last names starting with letters A-M and last names starting with letters N-Z

Homework Pg.104: #3.2, 3.9, 3.13, 3.14 Reading Notes 3.2