Statistics Chapter 1

Statistics

The science of collecting, organizing, analyzing
and interpreting data in order to make decisions.

Descriptive Statistics

involves organizing,
summarizing and displaying data.

Inferential Statistics

involves using sample data
to draw conclusions about a population.

Population

consists of all subjects (humans,
animals, etc.) that are being studied.

Sample

a subset of the population. Example:

A survey of 2000 households in the U.S. found that
65% subscribe to cable TV.

Sample: 2000 households surveyed

Population: All households in the U.S.

Parameter

a characteristic or measurement obtained
by using the data in the population.

The freshman class at a university has an average
SAT math score of 51414

Parameter.

Statistic

a characteristic or measurement obtained by
using the data in the sample.

A survey of 500 collegiate student-athletes in the U.S. found that the average time spent on athletics by
student-athletes is 50 hours per week

Statistic

Qualitative Data

consists of attributes, labels,
nonnumerical values.

Quantitative Data

numerical measurements

Random Sample

each member of the
population has an equal chance of being
selected.

Simple Random Sample

Every possible
sample of the same size has the same chance
of being selected.

Stratified Sampling

divide the population into
groups with similar characteristics and select a
sample from each group.p.

Cluster Sampling

divide the population into
same size groups and randomly select 1 or
more groups but not all.

Systematic Sampling

choose a starting point
and select members at regular intervals.als.

Convenience Sampling

choose readily
available members of a population. Often leads
to biased samples.

Observational Study

A researcher observes what is happening (or
happened) and draw conclusions based on their
observations.

Observe teachers in a classroom,
observe animals in their natural habitat.

Observational Study

Experimental Study

A researcher applies a treatment to part of a
population, called a treatment group, and
responses are recorded

Blind Experiment

participants do not know
whether they are receiving the treatment or a
placebo.

Double-Blind Experiment

neither the participant nor the experimenter knows if the

Simulation

A researcher uses mathematical models to
reproduce conditions of a situation or process.

Ex: rCrash test dummies, computers to simulate
airplane landings or process.

Survey

An investigation of one or more characteristic of a
population.

Ex: survey through the mail, phone, in person
or online.

Size of sample? Selection process? Convenience
Sample?

Suspect Samples

Ex: Candidate states, “During my candidacy I
increased expenditures a mere 3% and my opponent
increased them by $6,000,000!

Changing the subject

Ex: Eating fish may help to reduce your
cholesterol.
 Studies suggest that using our exercise machine
will help you lose weight.

Implied Connections

Detached Statistics

Ex: Our brand of crackers has one-third fewer
calories.
 Ex: Our aspirin works four times faster

What are the advantages of an open​ question?

• An open question allows the respondent to go​ in-depth with their answer.

• An open question allows for new solutions to be introduced.

What are the disadvantages of an open​ question?

• the form of the question may influence the opinion of the respondent.

• It is difficult to quantify the responses of open questions.

• It is difficult to compare the results of surveys with open questions.

What are the advantages of a closed​ question?

• it is possible to automate the collection of results for closed questions.

• It is easy to quantify and compare the results of surveys with closed questions.

What are the disadvantages of a closed​ question?

• Closed questions may not provide appropriate alternative responses.

• The form of the question may influence the opinion of the respondent.

What are some benefits of representing data sets using frequency​ distributions?

Organizing the data into a frequency distribution can make patterns within the data more evident.

What are some benefits of using graphs of frequency​ distributions?

It can be easier to identify patterns of a data set by looking at a graph of the frequency distribution.