Introduction to the Practice of Statistics

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Section 1.1 - Introduction to the Practice of Statistics

1.Explain the difference between a population and a sample. A population is the entire group to be studied and a sample is a portion of the population.

2.Explain the difference between a parameter and a statistic. A statistic is a numerical summary of a sample and a parameter is a numerical summary of a population.

3.What is Descriptive Statistics and how is it used?
Descriptive statistics describes the results of a sample without making conclusions of the population.

4.What is Inferential Statistics and how is it used?
Inferential statistics uses the result of a sample to apply to a population.

5.Determine whether the following variables are qualitative or quantitative.

VariableType of Variable
Number of siblingsQuantitative
The number of a football player's jerseyQualitative
The assessed value of a houseQuantitative
The day of the weekQualitative

6.Determine whether the following quantitative variables are continuous or discrete.

VariableType of Variable
Volume of water lost each day through a leaky faucetContinuous Number of trees on a randomly selected acre of land Discrete Internet connection speed in kilobytes per secondContinuous Air pressure in pounds per square inch in an automobile tireContinuous

7.Determine whether the following underlined variable is a parameter or statistic.

VariableType of Variable
Calculus Exam: In the Spring 2008 semester a college had a total of 11 Calculus 101 classes. The average score for one class of 25 students taking the Calculus 101 midterm exam was 72%.Statistic Calculus Exam: The average score for a class of 28 students taking a calculus midterm exam was 84%.Parameter Moonwalkers: Only 12 men have walked on the moon. The average age of these 12 men is at the time of their moonwalks was 39 years, 11 months, 15 days.Parameter Alcohol Use: In a national survey on substance abuse, 66.4% of respondents who were 18 years old to 20 years old reported using alcohol during the previous month. Statistic

8.List and briefly describe the four different Levels of Measurement of a Variable. 1. Nominal – A nominal level of measurement is when the value is a name, label, or category that cannot be arranged in a specific order. 2. Ordinal – An ordinal level of measurement is when the value is a name, label, or category that can be arranged in a specific order. 3. Interval – An interval level of measurement is when the value of the variable has meaning and when the value of zero does not mean the absence of the quantity. Arithmetic operations such as addition and subtraction can be performed on the value of the variable. 4. Ratio – A ration level of measurement is when the value of the variable has meaning and when the value of zero represents the absence of the quantity. Arithmetic operation such as multiplication and division can be performed on the value of the variable.

9.Determine the Level of Measurement (Nominal, Ordinal, Interval, or Ratio) for the following variables.

VariableLevel of Measurement
Movie ratings of one star through five starsInterval
The amount of time to run one mileRatio
The day of the weekOrdinal
The first five finishers of a raceNominal

10.Given the following research objective: A quality-control manager randomly selects 50 bottles of Coca-Cola that were filled on October 1 to assess the calibration of the filling machine.

a)Identify the population and sample in the study.
The population is all bottles of Coca-Cola that were filled on October 1. The sample is the 50 selected bottles.

11.Given the following research objective: Every year the U.S. Census Bureau releases the Current Population Report based on a survey of 50,000 households. The goal of this report is to determine the demographic characteristics, such as family size and income, of all households within the United States.

a)...
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