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Section 1.1

Section 1.1. Getting Started. Objectives. Learn the basic vocabulary of statistics. Distinguish between population and sample; parameters and statistics. Getting Started. Statistics Statistics is the science of gathering, describing, and analyzing data. OR

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Section 1.1

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  1. Section 1.1 Getting Started

  2. Objectives Learn the basic vocabulary of statistics. Distinguish between population and sample; parameters and statistics.

  3. Getting Started Statistics Statistics is the science of gathering, describing, and analyzing data. OR Statistics are the actual numerical descriptions of sample data.

  4. Getting Started A populationis a particular group of interest. A variable is a value or characteristic that changes among members of the population. Data are the counts, measurements, or observations gathered about a specific variable in a population in order to study it. A census is a study in which data are obtained from every member of the population.

  5. Getting Started A parameter is a numerical description of a population characteristic. A sample is a subset of the population from which data are collected. Sample statistics are numerical descriptions of sample characteristics.

  6. Getting Started

  7. Example 1.1: Identifying Population and Sample Identify the population and the sample. a. In a survey, 359 college students at the University of Jackson were asked if they had tried the October flavor of the month at the campus coffee shop. Eighty‑three of the students surveyed said yes. b. A survey of 1125 households in the United States found that 24% subscribe to satellite radio.

  8. Example 1.1: Identifying Population and Sample (cont.) Solution a. Population: All college students at the University of Jackson Sample: The 359 college students who were surveyed b. Population: All households in the United States Sample: The 1125 households in the United States that were surveyed

  9. Example 1.2: Identifying Population, Sample, Parameters, and Statistics Read each of the shortened survey reports below. For each report: a. Identify the population. b. Identify the sample. c. Determine whether the highlighted value is a parameter or statistic.

  10. Example 1.2: Identifying Population, Sample, Parameters, and Statistics (cont.) I. After an airplane security scare on Christmas day, 2009, the Gallup organization interviewed 542 American air travelers about increased security measures at airports. The report stated that 78%of American air travelers are in favor of United States airports using full-body‑scan imaging on airline passengers. Source: Jones, Jeffrey M. “In U.S., Air Travelers Take Body Scans in Stride.” 11 Jan. 2010. http://www.gallup.com/poll/125018/Air-Travelers-Body-Scans-Stride.aspx (12 Dec. 2011).

  11. Example 1.2: Identifying Population, Sample, Parameters, and Statistics (cont.) II. Rasmussen Reports also conducted a survey in response to the airport security scare on Christmas day, 2009. The national telephone survey of 1000 adult Americans found that 59% of Americans surveyed favor racial profiling as a means of determining which passengers to search at airport security checkpoints. Source: Rasmussen Reports. “59% Favor Racial, Ethnic Profiling For Airline Security.” 7 Jan. 2010. http://www.rasmussenreports.com/public_content/lifestyle/general_lifestyle/january_2010/59_favor_racial_ethnic_profiling_for_airline_security (12 Dec. 2011).

  12. Example 1.2: Identifying Population, Sample, Parameters, and Statistics (cont.) Solution I. a. Population: All American air travelers b. Sample: The 542 American air travelers who were surveyed c. The value 78% refers to all American air travelers; thus this is a population parameter.

  13. Example 1.2: Identifying Population, Sample, Parameters, and Statistics (cont.) II. a. Population: All adult Americans b. Sample: The 1000 adult Americans who were surveyed c. The value 59% refers to only those adult Americans who were surveyed, thus this is a sample statistic.

  14. Branches of Statistics The branch of descriptive statistics, as a science, gathers, sorts, summarizes, and displays the data. The branch of inferential statistics, as a science, involves using descriptive statistics to estimate population parameters.

  15. Example 1.3: Identifying Descriptive and Inferential Statistics In a news report on the state of the media by Tom Rosenstiel and Amy Mitchell, they write the following: “AOL had 900 journalists, 500 of them at its local Patch news operation.... By the end of 2011, Bloomberg expects to have 150 journalists and analysts for its new Washington operation, Bloomberg Government.” Source: Rosenstiel, Tom and Amy Mitchell. “Overview.” The State of the News Media: An Annual Report on American Journalism. Pew Research Center’s Project for Excellence in Journalism. 2011. http://stateofthemedia.org/2011/overview-2/ (12 Dec. 2011). Identify the descriptive and inferential statistics used in this excerpt from their article.

  16. Example 1.3: Identifying Descriptive and Inferential Statistics (cont.) Solution When the authors identify AOL as having “had 900 journalists, 500 of them at its local Patch news operation,” they are describing the actual counts, not estimates; thus these numbers of journalists are descriptive statistics. On the other hand, when the authors state “By the end of 2011, Bloomberg expects to have 150 journalists and analysts for its new Washington operation,” they are referring to an estimate based on past descriptive statistics. Therefore the estimate, 150 journalists and analysts, is an inferential statistic.

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