In an increasingly data-driven world, it is more important than ever for students as well as professionals to better understand basic statistical concepts. 100 Questions (and Answers) About Statistics addresses the essential questions that students ask about statistics in a concise and accessible way. It is perfect for instructors, students, and practitioners as a supplement to more comprehensive materials, or as a desk reference with quick answers to the most frequently asked questions.

# How Can the Reliability of a Test Be Increased?

### How Can the Reliability of a Test Be Increased?

If you remember, the formula for reliability is

$\text{Reliability}\phantom{\rule{0.5em}{0ex}}=\phantom{\rule{0.5em}{0ex}}\frac{\text{True}\phantom{\rule{0.5em}{0ex}}\text{score}}{\text{True}\phantom{\rule{0.5em}{0ex}}\text{score}\phantom{\rule{0.5em}{0ex}}+\phantom{\rule{0.5em}{0ex}}\text{Error}\phantom{\rule{0.5em}{0ex}}\text{score}}$

and the lower the amount of error score in the formula, the closer the reliability coefficient is to the true score and the more perfect the assessment.

You can see in the equation below that error score is composed of two elements: trait error and method error.

$\text{Error}\phantom{\rule{0.5em}{0ex}}\text{score}\phantom{\rule{0.5em}{0ex}}=\phantom{\rule{0.5em}{0ex}}\text{Trait}\phantom{\rule{0.5em}{0ex}}\text{error}\phantom{\rule{0.5em}{0ex}}+\phantom{\rule{0.5em}{0ex}}\text{Method}\phantom{\rule{0.5em}{0ex}}\text{error}$

Trait error is due to individual differences between test takers, such as the amount of time they study, how well prepared they are in general, their state of health, and their motivation. Method error is due to those differences that are not characteristic of an individual, such as the physical properties of the test, the location of the test, and how comfortable test ...

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