##### Statistics 146

Statistics.

The science of

collecting

organizing

analyzing,

interpreting data in order to make scientifically based decisions.

Descriptive Statistics

The organizing, summarizing, and displaying of data.

Inferential Statistics.

Using samples to draw conclusions about populations

Variable

The characteristic that is being measured or observed. The variable will generally be labeled on the X-axis .

Qualitative Variable.

Data consisting of

attributes or labels.

Quantitative Variable.

Data consisting of pure

numerical
measurements.

Scatter Plot.

A graph that shows paired data, rather than just data in classes like a histogram. The data shows the correlation between two variables.

Data Collection

•
Take A Census.

Measure the entire population.

Data Collection

Take A Sample

Measure part of the population

Data Collection

Perform Experiments.

Induce treatments, observe responses.

P arameter.

A numerical description of a population characteristic

S tatistic.

A numerical description of a sample characteristic

P opulation. .

The collection of all outcomes, responses, and measurements.

S ample.

A subset of a population

Random Sample

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

Random .

1. Having a value that can not be determined before the
value is taken, but can only be determined
probabilistically (such as a random variable).

2. Chosen without regard to any characteristics of the
individual members of the population so that each
member has an equal chance of being selected.

Stratified Sample.

Taking samples from each segment of the population.

Cluster Sample.
.

A sample taken from a population that contains naturally occurring subgroups

Systematic Sample.

Each member is selected at orderly intervals.

Convenience Sample.

A sample which consists of only readily available elements.

Distributions Using a Histogram

• Cumulative Frequency Distribution (Ogive) .

A graph that shows the cumulative total of each data count.

Distributions Using a Histogram

• Frequency Distribution.

A histogram that shows classes (intervals) of data counts.

Distributions Using a Histogram

• Relative Frequency Distribution .

A histogram that shows the percent of data that falls into classes (intervals).