Descriptive Statistics

What are the three measures of central tendency?

Mean, median, and mode.

What is the mean?

The arithmetic average of all scores.

What is the median?

The middle score when data are arranged in order.

What is the mode?

The most frequently occurring score.

How do you calculate the mean?

Add all scores together and divide by the total number of scores.

How do you calculate the median?

Order scores and find the middle value (or the average of the two middle values if there is an even number).

How do you calculate the mode?

Identify the score that appears most often.

What are measures of dispersion?

Values that show the spread or variability of data.

What are the two main measures of dispersion?

Range and standard deviation.

What is the range?

The difference between the highest and lowest scores.

How do you calculate the range?

Highest score minus lowest score.

What is a strength of the range?

Simple and quick to calculate.

What is a limitation of the range?

Affected by extreme values; doesn’t show data distribution.

What is standard deviation?

A measure of the average distance of each score from the mean.

What does a small standard deviation show?

Data are clustered closely around the mean (low variability).

What does a large standard deviation show?

Data are spread out widely around the mean (high variability).

How do you calculate a percentage?

(Part ÷ Whole) × 100.

What does a positive correlation show?

As one variable increases, the other also increases.

What does a negative correlation show?

As one variable increases, the other decreases.

What does a zero correlation show?

No relationship between the two variables.

Which measure of central tendency is most affected by extreme values?

The mean.

Which measure of central tendency is least affected by extreme values?

The median.

Which measure of central tendency is used for nominal data?

The mode.

Which measure of central tendency is used for ordinal data?

The median.

Which measure of central tendency is used for interval/ratio data?

The mean.

What is one strength of the mean?

Uses all data, making it representative.

What is one limitation of the mean?

Can be distorted by extreme scores.

What is one strength of the median?

Unaffected by extreme values.

What is one limitation of the median?

Less sensitive; ignores exact values.

What is one strength of the mode?

Easy to calculate; suitable for categorical data.

What is one limitation of the mode?

Not useful with multiple modes or evenly spread data.