Chapter 1: What is Statistics?

(a) the mean age of people who listen to talk radio is 42.1 years. What level of measurement is used to assess the variable age? (b) In a survey of luxury-car owners, 8% of the U.S. population own luxury cars. In California and Georgia, 14% of people own luxury cars. Two variables are included in this information. What are they and how are they measured?

(a) Age is a ratio-scale variable. A 40-year-old is twice as old as someone 20 years old (b) The two variables are: (1) if a person owns a luxury car, and (2) the state of residence. Both are measured on a nominal scale

The Atlanta-based advertising firm Brandon and Associates asked a sample of 1,960 consumers to try a newly developed chicken dinner by Boston Market. Of the 1,960 sampled, 1,176 said they would purchase the dinner if it were marketed (a) Is this an example of descriptive statistics or inferential statistics? (b) What could Brandon and Associates report to Boston Market regarding the acceptance of the chicken dinner in the population?

(a) Inferential Statistics, because a sample was used to draw a conclusion about how all consumers in the population would react if the chicken dinner were marketed (b) On the basis of the sample of 1,960 consumers, we estimate that, if it is marketed, 60% of all consumers will purchase the chicken dinner: (1,176 / 1,960) x 100 = 60%

Population

the entire set of individuals or objects of interest or the measurements obtained from all individuals or objects of interest

inferential statistics

the methods used to estimate a property of a population on the basis of a sample

A poll solicits a large number of college undergraduates for information on the following variables: the name of their cell phone provider (AT&T, Verizon, and so on), the numbers of minutes used last month (200, 400, for example), and their satisfaction with the service (Terrible, Adequate, Excellent, and so forth). What is the level of measurement for each of these three variables?

- The cell phone provider: Nominal - The number of minutes used: Ratio - Satisfaction with the service: Ordinal

Sample

A portion, or part, of the population of interest

AVX Home Entertainment Incorporated recently began a "no-hassles" return policy. A sample of 500 customers who recently returned items showed 400 thought the policy was fair, 32 thought it took too long to complete the transaction, and the rest had no opinion. On the basis of this information, make an inference about customer reaction to the new policy. (Round your answers to 1 decimal place.)

Customer Reaction-Percent - Fair: 80% - Too long: 6.4% - No opinion: 13.6% The above data suggest that the majority of the customers: believe the policy is fair

Ratio level of measurement

Data recorded at the level of measurement are based on a scale with a known unit of measurement and a meaningful interpretation of zero on the scale

Nominal Level of Measurement

Data recorded at the nominal level of management are represented as labels or names. They have no order. They can only be classified and counted

Ordinal level of measurement

Data recorded at the ordinal level of measurement is based on a relative ranking or rating of items based on a defined attribute or qualitative variable. Variables based on this level of measurement are only ranked or counted

interval level of measurement

For data recorded at the interval level of measurement, the interval or the distance between values is meaningful. The interval level of measurement is based in a scale with a known unit of measurement

Descriptive Statistics

Methods of organizing, summarizing, and presenting data in an informative way

Statistics

The science of collecting, organizing, presenting, analyzing, and interpreting data to assist in making more effective decisions.

What is the level of measurement for each of the following variables? a. Student IQ ratings b. Distance students travel to class c. The jersey numbers of a sorority soccer team d. A student's state of birth e. A student's academic class--that is, freshman, sophomore, junior, or senior f. Number of hours students study per week

a. Interval b. Ratio c. Nominal d. Nominal e. Ordinal f. Ratio

For the following situations, would you collect information using a sample or a population? a. To find how many books are published in one week by a famous publishing company. b. To test a new drug produced by a biotech company. c. To find the number of men and women working in an IT company with 600 people. d. To estimate the average salary of doctors in California.

a. population b. Sample c. Population d. Sample

Classify the following as a population or sample: a. All immigrants to the United States in 2005 b. A few drops of blood from a patient for blood-typing

a. population b. sample