1 Business 90: Business Statistics Professor David Mease Sec 03, T R 7:30-8:45AM BBC 204 Lecture 9 = Start Chapter “Numerical Descriptive Measures” (NDM) Agenda: 1) Go over Homework 3 2) Assign Homework 4 (due Thursday 3/4) 3) Announce Midterm Exam (3/16) 4) Lecture over first part of Chapter NDM 5) Take quiz over Homework 3

2 Homework 3 - Due Tuesday 2/23 1) The dataset at gives the letter grades for a quiz I gave once. a) Make a summary table for the letter grades using the PivotTable in Excel. In your summary table list the grades in the order A+, A, A-, B+, etc. Double check a few of your answers by hand. b) Make the bar chart using Excel with the grades in the same order as in part A. c) Make the pie chart using Excel. d) Make the pareto diagram using Excel. 2) The dataset contains flight status information for America West flights departing from four major West Coast airports. Make a contingency table for this data using the PivotTable feature in Excel. 3) Do textbook problem number 48 in Chapter “Presenting Data in Tables and Charts”. 4) The dataset at contains data from 20 San Jose State University graduating seniors who were asked to report their high school GPA (first column) and their current college GPA (second column). a) Make a scatter plot of this data with High School GPA on the X-axis and College GPA on the Y-axis using Excel. b) Give the equation of the least squares regression line using Excel. c) What is the slope of the least squares regression line? d) Interpret the slope of the least squares regression line. e) What is the coefficient of correlation? f) What is the value of R-squared? g) Use the least squares regression line to predict the college GPA of a student who had a high school GPA of 2.7. Important: Again, be sure to print out your solutions and bring them with you to class for the quiz.

3 Homework 4 – Due Thursday 3/4 1) Read chapter entitled “Numerical Descriptive Measures”. 2) In that chapter do textbook problems 5, 8 and 9 by hand AND check the answers using Excel. 3) The data at ( gives free throw percentages for NBA basketball players for the season. a) Give the 5 number summary for the free throw percentages. b) Graph the box-and-whisker plot by hand. c) Based on your box-and-whisker plot, describe the shape of the data as left-skewed, symmetric or right-skewed. d) Use Excel to compute the mean, variance and standard deviation. e) Using your values from part d, give the empirical rule for this data. 4) Review In Class Exercise #46. (There will be one like this on the quiz.)

4 Announcement: Midterm Exam on Tuesday, March 16 You will NOT be able to use Excel or any notes for the exam, so make sure you know how to do everything by hand (with the help of a calculator). Be sure to bring your calculator. The exam will cover chapters IADC, PDITAC (plus least squares regression from p ), NDM and BP. Worth 100 points Seats will be assigned when you enter the room.

5 Numerical Descriptive Measures Statistics for Managers Using Microsoft ® Excel 4 th Edition

6 Chapter Topics Measures of central tendency, variation, and shape Mean, median, mode, geometric mean Quartiles Range, interquartile range, variance and standard deviation, coefficient of variation Symmetric and skewed distributions Population summary measures Mean, variance, and standard deviation The empirical rule Five number summary and box-and-whisker plots Coefficient of correlation

7 Summary Measures Arithmetic Mean Median Mode Describing Data Numerically Variance Standard Deviation Coefficient of Variation Range Interquartile Range Geometric Mean Skewness Central TendencyVariationShapeQuartiles

8 In class exercise #29: A sample of n=9 runners were asked how many miles they ran last week. Here is the data: Describe the center of this data. (What are the mean, median and mode?)

9 In class exercise #30: How would your answer change for ICE #29 if the first runner actually ran 143 miles instead of 43? Here is the data:

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11 In class exercise #31: How would your answer change for ICE #29 if there was a 10 th runner who also ran 17 miles? Here is the data:

12 Summary Measures Arithmetic Mean Median Mode Describing Data Numerically Variance Standard Deviation Coefficient of Variation Range Interquartile Range Geometric Mean Skewness Central TendencyVariationShapeQuartiles

13 Quartiles Quartiles split the ranked data into 4 segments with an equal number of values per segment 25% The first quartile, Q 1, is the value for which 25% of the observations are smaller and 75% are larger Q 2 is the same as the median (50% are smaller, 50% are larger) Only 25% of the observations are greater than the third quartile Q1Q2Q3

14 In class exercise #32: Compute the quartiles for the n=9 runners

15 In class exercise #33: Compute the quartiles for the n=10 runners

16 Quartile Formulas Find a quartile by determining the value in the appropriate position in the ranked data, where First quartile position: Q 1 at (n+1)/4 Second quartile position: Q 2 at (n+1)/2 (the median) Third quartile position: Q 3 at 3(n+1)/4 where n is the number of observed values

17 In class exercise #34: Redo ICE #32 and ICE #33 using these formulas and check that the answers are the same.