1 1 Slide © 2001 South-Western /Thomson Learning  Anderson  Sweeney  Williams Anderson  Sweeney  Williams  Slides Prepared by JOHN LOUCKS  CONTEMPORARYBUSINESSSTATISTICS WITH MICROSOFT  EXCEL CONTEMPORARYBUSINESSSTATISTICS

2 2 Slide Chapter 1 Data and Statistics n Applications in Business and Economics n Data n Data Sources n Descriptive Statistics n Statistical Inference n Statistical Analysis using Microsoft  Excel

3 3 Slide Applications in Business and Economics n Accounting Public accounting firms use statistical sampling procedures when conducting audits for their clients. n Finance Financial advisors use a variety of statistical information, including price-earnings ratios and dividend yields, to guide their investment recommendations. n Marketing Electronic point-of-sale scanners at retail checkout counters are being used to collect data for a variety of marketing research applications.

4 4 Slide n Production A variety of statistical quality control charts are used to monitor the output of a production process. n Economics Economists use statistical information in making forecasts about the future of the economy or some aspect of it. Applications in Business and Economics

5 5 Slide Data n Elements, Variables, and Observations n Qualitative and Quantitative Data n Cross-Sectional and Time Series Data

6 6 Slide Data and Data Sets n Data are the facts and figures that are collected, summarized, analyzed, and interpreted. n The data collected in a particular study are referred to as the data set.

7 7 Slide Elements, Variables, and Observations n The elements are the entities on which data are collected. n A variable is a characteristic of interest for the elements. n The set of measurements collected for a particular element is called an observation. n The total number of data values in a data set is the number of elements multiplied by the number of variables.

8 8 Slide Data, Data Sets, Elements, Variables, and Observations Elements Stock Annual Earn/ Stock Annual Earn/ Company Exchange Sales($M) Sh.($) DataramAMEX EnergySouth OTC Keystone NYSE LandCare NYSE PsychemedicsAMEX Variables Data Set Datum Observation

9 9 Slide Qualitative and Quantitative Data n The statistical analysis that is appropriate depends on whether the data for the variable are qualitative or quantitative. n Qualitative data are labels or names used to identify an attribute of each element. n Quantitative data indicate either how much or how many. n Quantitative data are always numeric. n Qualitative data can be either numeric or nonnumeric. n Ordinary arithmetic operations are meaningful only with quantitative data.

10 Slide Cross-Sectional and Time Series Data n Cross-sectional data are collected at the same or approximately the same point in time. Example: data detailing the number of building permits issued in June 2000 in each of the counties of TexasExample: data detailing the number of building permits issued in June 2000 in each of the counties of Texas n Time series data are collected over several time periods. Example: data detailing the number of building permits issued in Travis County, Texas in each of the last 36 monthsExample: data detailing the number of building permits issued in Travis County, Texas in each of the last 36 months

11 Slide Data Sources n Existing Sources Data needed for a particular application might already exist within a firm. Detailed information is often kept on customers, suppliers, and employees for example.Data needed for a particular application might already exist within a firm. Detailed information is often kept on customers, suppliers, and employees for example. Substantial amounts of business and economic data are available from organizations that specialize in collecting and maintaining data.Substantial amounts of business and economic data are available from organizations that specialize in collecting and maintaining data. Government agencies are another important source of data.Government agencies are another important source of data. Data are also available from a variety of industry associations and special-interest organizations.Data are also available from a variety of industry associations and special-interest organizations.

12 Slide Data Sources n Internet The Internet has become an important source of data.The Internet has become an important source of data. Most government agencies, like the Bureau of the Census ( make their data available through a web site.Most government agencies, like the Bureau of the Census ( make their data available through a web site. More and more companies are creating web sites and providing public access to them.More and more companies are creating web sites and providing public access to them. A number of companies now specialize in making information available over the Internet.A number of companies now specialize in making information available over the Internet.

13 Slide n Statistical Studies Statistical studies can be classified as either experimental or observational.Statistical studies can be classified as either experimental or observational. In experimental studies the variables of interest are first identified. Then one or more factors are controlled so that data can be obtained about how the factors influence the variables.In experimental studies the variables of interest are first identified. Then one or more factors are controlled so that data can be obtained about how the factors influence the variables. In observational (nonexperimental) studies no attempt is made to control or influence the variables of interest.In observational (nonexperimental) studies no attempt is made to control or influence the variables of interest. A survey is perhaps the most common type of observational study.A survey is perhaps the most common type of observational study. Data Sources

14 Slide Data Acquisition Considerations n Time Requirement Searching for information can be time consuming.Searching for information can be time consuming. Information might no longer be useful by the time it is available.Information might no longer be useful by the time it is available. n Cost of Acquisition Organizations often charge for information even when it is not their primary business activity.Organizations often charge for information even when it is not their primary business activity. n Data Errors Using any data that happens to be available or that were acquired with little care can lead to poor and misleading information.Using any data that happens to be available or that were acquired with little care can lead to poor and misleading information.

15 Slide Descriptive Statistics n Descriptive statistics are the tabular, graphical, and numerical methods used to summarize data.

16 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 below.

17 Slide Example: Hudson Auto Repair n Tabular Summary (Frequencies and Percent Frequencies Parts Percent Parts Percent Cost ($) Frequency Frequency Cost ($) Frequency Frequency Total Total

18 Slide Example: Hudson Auto Repair n Graphical Summary (Histogram) Parts Cost ($) Parts Cost ($) Frequency

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

20 Slide Statistical Inference n Statistical inference is the process of using data obtained from a small group of elements (the sample) to make estimates and test hypotheses about the characteristics of a larger group of elements (the population).

21 Slide Example: Hudson Auto Repair n Process of Statistical Inference 1. Population consists of all tune-ups. Average cost of parts is unknown unknown. 2. A sample of 50 engine tune-ups is examined. 3. The sample data provide a sample average cost of $79 per tune-up. 4. The value of the sample average is used to make an estimate of the population average. the population average.

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

23 Slide Using Excel for Statistical Analysis n In using Excel for statistical analysis, 3 tasks might be needed. Enter DataEnter Data Enter Functions and FormulasEnter Functions and Formulas Apply ToolsApply Tools

24 Slide Using Excel for Statistical Analysis n Data Set Note: Rows are not shown.

25 Slide Using Excel for Statistical Analysis n Formula Worksheet Note: Rows and Columns A-B are not shown.

26 Slide Using Excel for Statistical Analysis n Value Worksheet Note: Rows and Columns A-B are not shown.

27 Slide End of Chapter 1