---
url: "https://questionstar.com/principles-of-survey-research/chapter-2/slide-073.html"
title: "The True-Score Model"
type: "lehrbuch-slide"
chapter: 2
chapterTitle: "Survey: Measurement and Scaling"
slide: 73
---

# The True-Score Model

*The result of a measurement is not the true value of a characteristic, but only an observation of it.*

The result of a measurement is **not** the true value of a characteristic, but only an **observation** of it.

![Caliper](/principles-of-survey-research/media/caliper.png)

XOobserved = XTtrue + XSsystematic + XRrandom

XO observed value of a characteristic

XT the true value of the characteristic

XS systematic error

XR random error

---

*Slide 73 of 274 · Chapter 2: Survey: Measurement and Scaling · Principles of Survey Research · Dr. Paul Marx*