Courses/Behavioral Research: Statistical Methods

Behavioral Research: Statistical Methods

CG3.402

Vinoo Alluri•Monsoon 2025-26•4 credits

Revision Notes/Unit 2 — Research Design & Measurement

Unit 2 — Research Design & Measurement

Operational definitions, the four scales of measurement (NOIR), reliability (test-retest, inter-rater, parallel forms, internal consistency), and validity (internal, external, construct, face, ecological).

Scales, Reliability, Validity

13 min

Before any test, you must (1) **operationally define** the construct (how do you measure 'depression'?), (2) decide what **scale** it lives on (NOIR: Nominal/Ordinal/Interval/Ratio), and (3) establish that the measurement is both **reliable** (consistent) and **valid** (captures the construct). The two are independent: a bathroom scale that always reads 5 kg high is *reliable but not valid*; a stopped clock is reliable but invalid. You cannot be valid without being reliable. These distinctions drive every test choice in the course.