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Unformatted text preview: Chapter 2: Statistical Measures Chapter 2: Statistical Measures Keith E. Emmert Department of Mathematics Tarleton State University June 7, 2011 Chapter 2: Statistical Measures Outline 1 Parameters and Statistics 2 Central Tendency of a Data Set 3 Variation or Spread of a Data Set Chapter 2: Statistical Measures Parameters and Statistics Some Basic Definitions The population is the entire group of objects or individuals under study, about which information is wanted. A unit is an individual object or person in the population. The units are often called subjects if the population consists of people. A sample is a part of the population that is actually used to get information. A variable is a characteristic of interest to be measured for each unit in the sample. The size of the population is denoted by the capital letter N . The size of the sample is denoted by the small letter n . Chapter 2: Statistical Measures Parameters and Statistics Example Population, Unit, Sample, Size N = 20 n = 5 Unit Population Sample Chapter 2: Statistical Measures Parameters and Statistics Some Basic Definitions A parameter is a numerical value that would be calculated using all of the values of the units in the population. A statistic is a numerical value that is calculated using all of the values of the units in a sample. Chapter 2: Statistical Measures Parameters and Statistics Example Parameter or Statistic? According to the Campus Housing Fact Sheet at a BigTen University, 60% of the students living in campus housing are instate residents. In a sample of 200 students living in campus housing, 56.5% were found to be instate residents. Circle your answer. 1 In this particular situation, the value of 60% is a (parameter, statistic). 2 In this particular situation, the value of 56.5% is a (parameter, statistic). Chapter 2: Statistical Measures Parameters and Statistics Definitions A unit is the item or object we observe. When the object is a person, we refer to the unit as a subject. An observation is the information or characteristic recorded for each unit. A characteristic that can vary from unit to unit is called a variable . A collection of observations on one or more variables is called a data set . Chapter 2: Statistical Measures Parameters and Statistics Definitions More About Variables Qualitative variables are those which classify the units into categories. The categories may or may not have a natural ordering to them. Qualitative variables are also called categorical variables. Quantitative variables have numerical values that are measurements (length, weight, and so on) or counts (of how many). Arithmetic operations on such numerical values do have meaning. A discrete variable can only take on a finite (or countable) number of values....
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This note was uploaded on 01/13/2012 for the course MATH 350 taught by Professor Keithemmert during the Summer '11 term at Tarleton.
 Summer '11
 KeithEmmert
 Statistics

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