1 1 Slide Data and Data Sets n Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. and summarized for presentation and interpretation. All the data collected in a particular study are referred All the data collected in a particular study are referred to as the data set for the study. to as the data set for the study.

2 2 Slide Stock Annual Earn/ Stock Annual Earn/ Exchange Sales($M) Share($) Data, Data Sets, Elements, Variables, and Observations Company Dataram Dataram EnergySouth EnergySouth Keystone Keystone LandCare LandCare Psychemedics Psychemedics NQ NQ N N N N NQ NQ N N Variables Element Names Names Data Set Observation

3 3 Slide Data can be further classified as being qualitative Data can be further classified as being qualitative or quantitative. or quantitative. Data can be further classified as being qualitative Data can be further classified as being qualitative or quantitative. or quantitative. The statistical analysis that is appropriate depends The statistical analysis that is appropriate depends on whether the data for the variable are qualitative on whether the data for the variable are qualitative or quantitative. or quantitative. The statistical analysis that is appropriate depends The statistical analysis that is appropriate depends on whether the data for the variable are qualitative on whether the data for the variable are qualitative or quantitative. or quantitative. In general, there are more alternatives for statistical In general, there are more alternatives for statistical analysis when the data are quantitative. analysis when the data are quantitative. In general, there are more alternatives for statistical In general, there are more alternatives for statistical analysis when the data are quantitative. analysis when the data are quantitative. Qualitative and Quantitative Data

4 4 Slide Qualitative Data Labels or names used to identify an attribute of each Labels or names used to identify an attribute of each element element Labels or names used to identify an attribute of each Labels or names used to identify an attribute of each element element Often referred to as categorical data Often referred to as categorical data Use either the nominal or ordinal scale of Use either the nominal or ordinal scale of measurement measurement Use either the nominal or ordinal scale of Use either the nominal or ordinal scale of measurement measurement Can be either numeric or nonnumeric Can be either numeric or nonnumeric Appropriate statistical analyses are rather limited Appropriate statistical analyses are rather limited

5 5 Slide Quantitative Data Quantitative data indicate how many or how much: Quantitative data indicate how many or how much: discrete, if measuring how many discrete, if measuring how many continuous, if measuring how much continuous, if measuring how much Quantitative data are always numeric. Quantitative data are always numeric. Ordinary arithmetic operations are meaningful for Ordinary arithmetic operations are meaningful for quantitative data. quantitative data. Ordinary arithmetic operations are meaningful for Ordinary arithmetic operations are meaningful for quantitative data. quantitative data.

6 6 Slide Descriptive Statistics Most of the statistical information in newspapers, magazines, company reports, and other publications consists of data that are summarized and presented in a form that is easy to understand. Most of the statistical information in newspapers, magazines, company reports, and other publications consists of data that are summarized and presented in a form that is easy to understand. Such summaries of data, which may be tabular, graphical, or numerical, are referred to as descriptive statistics. Such summaries of data, which may be tabular, graphical, or numerical, are referred to as descriptive statistics.

7 7 Slide Example: Hudson Auto Repair The manager of Hudson Auto would like to have a better understanding of the cost of parts used in the engine tune-ups performed in the shop. She examines 50 customer invoices for tune-ups. The costs of parts, rounded to the nearest dollar, are listed on the next slide.

8 8 Slide Example: Hudson Auto Repair Example: Hudson Auto Repair n Sample of Parts Cost ($) for 50 Tune-ups

9 9 Slide Tabular Summary: Frequency and Percent Frequency Tabular Summary: Frequency and Percent Frequency (2/50)100(2/50)100 Parts Cost ($) Cost ($) Parts Frequency Frequency PercentFrequency

10 Slide Graphical Summary: Histogram Graphical Summary: Histogram Parts Cost ($) Parts Cost ($) Frequency 50      Tune-up Parts Cost

11 Slide Numerical Descriptive Statistics Numerical Descriptive Statistics Hudson’s average cost of parts, based on the 50 Hudson’s average cost of parts, based on the 50 tune-ups studied, is $79 (found by summing the tune-ups studied, is $79 (found by summing the 50 cost values and then dividing by 50). 50 cost values and then dividing by 50). The most common numerical descriptive statistic The most common numerical descriptive statistic is the average (or mean). is the average (or mean).

12 Slide Statistical Inference PopulationPopulation SampleSample Statistical inference CensusCensus Sample survey  the set of all elements of interest in a particular study particular study  a subset of the population  the process of using data obtained from a sample to make estimates from a sample to make estimates and test hypotheses about the and test hypotheses about the characteristics of a population characteristics of a population  collecting data for a population  collecting data for a sample

13 Slide Process of Statistical Inference Process of Statistical Inference 1. Population consists of all tune-ups. Average cost of parts is unknown unknown. 1. Population consists of all tune-ups. Average cost of parts is unknown unknown. 2. A sample of 50 engine tune-ups is examined. 2. A sample of 50 engine tune-ups is examined. 3. The sample data provide a sample average parts cost of $79 per tune-up. 3. The sample data provide a sample average parts cost of $79 per tune-up. 4. The sample average is used to estimate the population average. population average. 4. The sample average is used to estimate the population average. population average.

14 Slide Statistical Analysis Using Microsoft Excel Statistical analysis typically involves working with Statistical analysis typically involves working with large amounts of data. large amounts of data. Computer software is typically used to conduct the Computer software is typically used to conduct the analysis. analysis. Frequently the data that is to be analyzed resides in a Frequently the data that is to be analyzed resides in a spreadsheet. spreadsheet. Modern spreadsheet packages are capable of data Modern spreadsheet packages are capable of data management, analysis, and presentation. management, analysis, and presentation. MS Excel is the most widely available spreadsheet MS Excel is the most widely available spreadsheet software in business organizations. software in business organizations.

15 Slide Statistical Analysis Using Microsoft Excel n 3 tasks might be needed: Enter Data Enter Data Enter Functions and Formulas Enter Functions and Formulas Apply Tools Apply Tools

16 Slide n Excel Worksheet (showing data) Note: Rows are not shown. Statistical Analysis Using Microsoft Excel

17 Slide n Excel Formula Worksheet Note: Columns A-B and rows are not shown. Statistical Analysis Using Microsoft Excel

18 Slide n Excel Value Worksheet Note: Columns A-B and rows are not shown. Statistical Analysis Using Microsoft Excel

19 Slide A frequency distribution is a tabular summary of A frequency distribution is a tabular summary of data showing the frequency (or number) of items data showing the frequency (or number) of items in each of several non-overlapping classes. in each of several non-overlapping classes. A frequency distribution is a tabular summary of A frequency distribution is a tabular summary of data showing the frequency (or number) of items data showing the frequency (or number) of items in each of several non-overlapping classes. in each of several non-overlapping classes. The objective is to provide insights about the data The objective is to provide insights about the data that cannot be quickly obtained by looking only at that cannot be quickly obtained by looking only at the original data. the original data. The objective is to provide insights about the data The objective is to provide insights about the data that cannot be quickly obtained by looking only at that cannot be quickly obtained by looking only at the original data. the original data. Ch. 2: Summarizing Qualitative Data Frequency Distribution

20 Slide Guests staying at Marada Inn were asked to rate the quality of their accommodations as being excellent, above average, average, below average, or poor. The ratings provided by a sample of 20 guests are: Above Average Above Average Below Average Below Average Above Average Above Average Average Average Above Average Above Average Average Average Above Average Above Average Below Average Below Average Poor Poor Excellent Excellent Above Average Above Average Average Average Above Average Above Average Below Average Below Average Poor Poor Above Average Above Average Average Average Frequency Distribution n Example: Marada Inn

21 Slide Frequency Distribution Poor Below Average Average Above Average Excellent Total 20 RatingFrequency

22 Slide Using Excel’s COUNTIF Function to Construct a Frequency Distribution n Excel Formula Worksheet Note: Rows 9-21 are not shown. Download Ch01-Ch02-CustomerRatings.xlsx

23 Slide n Excel Value Worksheet Using Excel’s COUNTIF Function to Construct a Frequency Distribution Note: Rows 9-21 are not shown.

24 Slide The relative frequency of a class is the fraction or The relative frequency of a class is the fraction or proportion of the total number of data items proportion of the total number of data items belonging to the class. belonging to the class. The relative frequency of a class is the fraction or The relative frequency of a class is the fraction or proportion of the total number of data items proportion of the total number of data items belonging to the class. belonging to the class. A relative frequency distribution is a tabular A relative frequency distribution is a tabular summary of a set of data showing the relative summary of a set of data showing the relative frequency for each class. frequency for each class. A relative frequency distribution is a tabular A relative frequency distribution is a tabular summary of a set of data showing the relative summary of a set of data showing the relative frequency for each class. frequency for each class. Relative Frequency Distribution

25 Slide Percent Frequency Distribution The percent frequency of a class is the relative The percent frequency of a class is the relative frequency multiplied by 100. frequency multiplied by 100. The percent frequency of a class is the relative The percent frequency of a class is the relative frequency multiplied by 100. frequency multiplied by 100. A percent frequency distribution is a tabular A percent frequency distribution is a tabular summary of a set of data showing the percent summary of a set of data showing the percent frequency for each class. frequency for each class. A percent frequency distribution is a tabular A percent frequency distribution is a tabular summary of a set of data showing the percent summary of a set of data showing the percent frequency for each class. frequency for each class.

26 Slide Relative Frequency and Percent Frequency Distributions Poor Below Average Average Above Average Excellent Total Relative RelativeFrequency Percent PercentFrequency Rating.10(100) = 10 1/20 =.05

27 Slide n Excel Formula Worksheet Note: Columns A-B and rows 9-21 and are not shown. Using Excel to Construct Relative Frequency and Percent Frequency Distributions

28 Slide n Excel Value Worksheet Using Excel to Construct Relative Frequency and Percent Frequency Distributions Note: Columns A-B and rows 9-21 and are not shown.