Levels of measurement

What are the four levels of measurement in psychology?

1. Nominal, 2. Ordinal, 3. Interval, 4. Ratio

What is Nominal data?

Data that represents categories or groups without any order. Example: Gender, eye color, types of mental disorders.

What is the Ordinal level of measurement?

Data that involves order or ranking, but the intervals between ranks are not equal. Example: Rank in a race (1st, 2nd, 3rd), Likert scales (e.g., strongly agree, agree, neutral).

What is the Interval level of measurement?

Data that has equal intervals between values, but no true zero point. Example: Temperature in Celsius or Fahrenheit.

What is the Ratio level of measurement?

Data that has a true zero point, and equal intervals between values. Example: Height, weight, time.

What is a key difference between Interval and Ratio data?

Interval data lacks a true zero point, while Ratio data has a true zero, allowing for meaningful ratios.

Can you perform all types of statistical analysis on Nominal data?

No. You can only perform frequency counts (mode) and percentages. Other statistical measures like mean or median are not suitable.

What types of data can you use the mean for?

Interval and Ratio data, as both have equal intervals and meaningful values that allow for averaging.

What is the mode used for?

The mode can be used for Nominal, Ordinal, Interval, and Ratio data. It represents the most frequent value in the dataset.

Can Ordinal data be used for calculating the mean?

No. The mean cannot be used for Ordinal data because the intervals between ranks are not necessarily equal.