Section 1.4 | Statistical Notation

Question 1

Identify the following symbols: X, Y, N, and n.

Answer 1

Raw scores are the original, unchaged scores obtained in a study. Scores for a particular variable are usually represented by the letter X.

When observations are made for two variables, there will be two scores for each individual. The data can be presented as two lists labeled X and Y.

The letter N is used to specify how many scores are in a set. An uppercase letter N identifies the number of scores in a population and a lowercase letter n identifies the number of scores in a sample.

Question 2

What is the summation notation?

Answer 2

The Greek letter sigma, or ∑, is used to stand for summation, the sum of a set of scores. The expression ∑X means to add all the scores for variable X.

• The summation sign is always followed by a sumbol or mathematical expression.
• The summation process is often included with several other mathematical operations. Following the correct order of operations must be done to get the correct answer.