Variables aggregation, composed Index, psychology, data setting

[Chiara Tasselli]

Good morning to everyone,
I would like to generate a synthetic index for students: "expectation of success" that is composed by:

• "measured ability" = mark in math (score from 1 to 10)

+

• "ability self-concept"=
  1. how much they feel skilled in math (score from 1 to 10) +
  2. the following item which scores from 1 to 4, 1 = strongly disagree and 4 = strongly agree
     • I am not good at math. (reversed)
     • I get good grades in mathematics
     • I learn mathematics quickly
     • In my maths class, I understand even the most difficult work.

What is the best way to aggregate them in order to get a good index?

Many thanks in advance for your time and suggestions!

[Carlo Lazzaro]

Chiara:
-pca- is the first tool that crosses my mind.

[Rich Goldstein]

h sem