Descriptive Statistics

Descriptive statistics are used to…?

describe the basic features of the sample and data

Descriptive stats are most helpful for…?

continuous, quantitative data

Descriptive stats provide simple _______ about the ______ and the ________ used to examine it

summaries; sample; measures

Combined with simple graphics analysis, descriptive stats form…?

the basis of virtually every quantitative analysis of data

Descriptive stats are _______ ___ inferential statistics

different from

Inferential statistics use a sample of data taken from a population to…?

make inferences about the population (perform statistical tests)

Descriiptive stats are almost always done, even when the main goal of a project involves ________ ______.

inferential statistics

Descriptive statistics help us understand what?

the sample and its generalizability

A sample must be generalizable in order to be…?

representative of the population from which it came

Measures of central tendency:

Examine the central value in a distribution of values

• Mean

• Median

• Mode

Mean

“average” of all the observations in a variable

• expresses a value that is typical for a group

• (μ)

The mean is useful because (2)

• Summarizes large amounts of data into a single value

• Represents some variability around this single value

The ____ is the most commonly used simple statistic

mean

What is one negative of using the mean?

It can be easily affected by outliers or skewed data and give biased results

The mean=

sum of data/number of data entries

Median

Middle value of all the observations in a variable

The ______ is a good measure of the average value when the data includes exceptionally high or low values

median

The ______ is the most suitable measure of

average for data classified on an ordinal scale

median

Mode

Most common value to occur in a variable

The ____ is most helpful when using nominal data.

mode

• ie. “most respondents chose option 2”

Range

The lowest and highest values of a variable

The range can be highly affected by ______ and considered more of a measure of _______.

outliers; variability