1.1 An Overview of Statistics

1.1 An Overview of Statistics
LEQ: How do you know if a data set is a population or a sample?
1. A Definition of Statistics:
a. Definition 1: _________ consist of information coming from observations,
counts, measurements, or responses.
b. Definition 2: __________________ is the science of collecting,
organizing, analyzing, and interpreting data in order to make decisions.
2. Data Sets:
a. Definition 3: A _____________________ is the collection of all
outcomes, responses, measurements, or counts that are of interest.
b. Definition 4: A _________________ is a subset of a population.
c. Example 1: Determine whether the data set is a population or a sample.
Explain your reasoning.
i. The age of each state governor (#11)
ii. The cholesterol levels of 20 patients in a hospital with 100 patients
d. Example 2: Identify the population and the sample.
i. In a recent survey, 3002 adults in the U.S. were asked if they read
news on the Internet at least once a week. Six hundred of the
adults said yes.
ii. A survey of 546 women found that more than 56% are the primary
investor in their household. (#23)
e. Definition 5: A ____________________ is a numerical description of a
population characteristic.
f. Definition 6: A __________________ is a numerical description of a
sample characteristic.
g. Example 3: Determine whether the numerical value is a parameter or a
statistic. Explain your reasoning.
i. A recent survey of a sample of MBAs reported that the average
starting salary for an MBA is less than $65,000.
ii. Starting salaries for the 667 MBA graduates from the University of
Chicago Graduate School of Business increased 8.5% from the
previous year.
iii. The average annual salary for 35 of a company’s 1200 accountants
is $68,000. (#25)
iv. In a recent year, the interest category for 12% of all new magazines
was sports. (#28)
3. Branches of Statistics:
a. Definition 7: _____________________________ is a branch of statistics
that involves the organization, summarization, and the display of data.
b. Definition 8: _____________________________is the branch of
statistics that involves using a sample to draw conclusions about a
population. A basic tool in the study of inferential statistics is probability.
c. Example 4: Decide which part of the study represents the descriptive
branch of statistics. What conclusions might be drawn from the study
using inferential statistics?
i. A large sample of men, aged 48, was studied for 18 years. For
unmarried men, approximately 70% were alive at age 65. For
married men, 90% were alive at age 65.
ii. In a sample of Wall Street analysts, the percentage who incorrectly
forecasted high-tech earnings in a recent year was 44%.
d. Example 5: Solve the following problem.
i. In a recent study, volunteers who had 8 hours of sleep were three
times more likely to answer correctly on a math test than were
sleep-deprived participants. (#34)
1. Identify the sample used in the study.
2. What is the sample’s population?
3. Which part of the study represents the descriptive branch of
4. Make an inference based on the results of the study.
4. HW: p. 6 (1 – 10 all, 12 – 36 mo3)