Population

the entire collection of people, animals, cells, or other things from which we collect data

Parameter

A number that is calculated from an entire population

Sample

A subset or group drawn from the population

Statistic

A number or quantity that is calculated from a sample of data

Descriptive Statistics

Statistics that describe the sample without attempting to generalize the results to other groups or populations

Inferential Statistics

Statistics that infer the likelihood that the results can be generalized to the population

Measure of Central Tendency

A single value that attempts to describe the central position of a set of data

Mean

Average Value

Median

Middle Value

Mode

Most frequent value

Measure of dispersion/variation

A value that describes how the data are dispersed around the measure of central tendency OR the extent to which individual values differ from the mean/median/mode

Standard Deviation

On average, how much individual values differ from the mean

Variance

How far a set of numbers is spread out from the mean

Range

The difference between the largest & smallest value in the data set

Interquartile Range

A measure of the "middle fifty" in the data set AKA the difference between first and third quartile of the data

Outlier

An observation point that is distant from other observations

Frequency

The number of times a value appears in the data set

Frequency Distribution

A table or graph that illustrates how frequently each value appears in the data set

Normal Distribution

A symmetric, bell-shaped distribution for a continuous variable

For a normal distribution.. __ % of observations fall within 1 standard devation, __ % of observations fall within 2 standard devations, and __ % of observations fall within 3 standard devations.

1 = 68% 2 = 95% 3 = 99.7%

Confidence Interval

An estimate of the population parameter that will contain the population mean a specified proportion of the time (usually 95% or 99%)

Probability

The likelihood that an event will occur

What descriptive data is NOT done for nominal data?

Median and Median (we just see frequency distributions and mode)

Statistics are sample values. What are their corresponding population values?

Parameters

What numbers describe the extent to which individual values differ from the mean?

Measures of dispersion

What does a standard deviation of 0 indicate?

All values in the data are the same.

In a normal distribution, what percentage of the values fall within two standard deviations of the mean?

95%

"What is your religion?" is a nominal scale measure. What measure of central tendency is appropriate to use in this instance?

Mode

One hundred participants answer the question, "How many songs did you download last week?" What is the appropriate measure of central tendency to use in this example?

Mean

What measure of dispersion is generally reported with the median?

Range

What describes the basic objective of descriptive statistics?

To summarize basic findings for the sample

What does it tell us if our P-value < Alpha?

The results are statistically significant.