What is the first step to be performed in the following mathematical expression, ΣX?

What is the first step to be performed in the following mathematical expression, ΣX?

• A. Square each score
• B. Add the scores
• C. Add the squared scores
• D. Square the sum of the scores

Answer: (B)

The main idea is that the summation symbol tells you to add up all the X values. So the first step is to compute the total of the scores: X1 plus X2 plus ... plus Xn. For example, if the data are 3, 7, and 2, you start by adding them to get 12. Only after you have this sum would you move on to any further calculation tied to ΣX, like calculating a mean by dividing by the number of observations. The other phrases describe different operations: squaring each score or squaring the total would pertain to different summation forms (like ΣX^2 or (ΣX)^2), not the first step for ΣX.

The main idea is that the summation symbol tells you to add up all the X values. So the first step is to compute the total of the scores: X1 plus X2 plus ... plus Xn. For example, if the data are 3, 7, and 2, you start by adding them to get 12. Only after you have this sum would you move on to any further calculation tied to ΣX, like calculating a mean by dividing by the number of observations. The other phrases describe different operations: squaring each score or squaring the total would pertain to different summation forms (like ΣX^2 or (ΣX)^2), not the first step for ΣX.