Understanding Standardized Test Scores

Instructor: Laura Gray

Laura has taught at the secondary and tertiary levels for 20+ years and has a Ph.D. in Instructional Design for Online Learning.

In this lesson, you'll learn about the basic terms used in standardized test scores, such as scoring curves and the standard deviation, which can help you explain test results to parents and students. You'll also discover how most students perform on standardized tests and have the chance to assess your new knowledge of the topic with a brief quiz.

Test Score Jargon

Stanines? Raw scores? Standard deviations? Percentiles? What do all these words mean? I just want to see how my students did on the test!

If these questions sound similar to the ones you've uttered the day that your school's standardized test scores came in, you are not alone. In fact, most people, teachers included, have a difficult time interpreting standardized test scores. Sifting through all the jargon can be nothing short of a nightmare, but the following lesson will walk you through the most common terms associated with test score interpretation, and in no time at all, you'll be fluent in the use of these often confusing terms.

Test Score Curves

What do terms like stanines, raw scores and standard deviations mean? Aren't they all just different ways of saying the same thing? The short answer to that second question is 'yes.' There are many ways to interpret test scores, and scholars have come up with literally dozens of terms for figuring out what these scores mean. Let's start with the basics.

When you were studying to be a teacher, you probably learned about the normal curve. Essentially, the normal curve provides us with an umbrella under which most students fall. Predictably, more students will fall toward the center of the umbrella than the ends, which is what gives the curve its 'bell' shape. The other term you need to remember is standard deviation. Over two thirds of students will fall between one standard deviation on either side of the center of that curve, meaning that the majority of students can be considered pretty much 'average' when it comes to taking a standardized test.

Standardized Test Terms

Once you remember that most test scores are distributed along the normal curve, and that most students fall within one standard deviation to either side of the center of that curve, it makes these other definitions easier to understand.

Stanine: This term literally means 'standard nine,' and test scores on most standardized tests will fall into one of nine stanines. The first stanine is the lowest 10%, the second is the next 10%, and so on... until you reach stanine number five, which comprises the middle 20%. After number five, each stanine increases by 10% increments. Scores from the fourth through sixth stanines are considered average, with lower scores being below average and higher scores falling in the above-average ranges. Grouping scores into stanines is just a handy way of letting you know how your students scored on a scale of one to nine.

Percentiles: The percentile, which is expressed as a number between one and 99, tells you how many of your particular students scored higher than 'x' percent of students in the norming group for that test. Contrary to what many people believe, it does not tell you that they did better than 'x' percent of students who took the test when they did! Again, most students will fall within one standard deviation of the 50th percentile. However, you'll need to read the fine print on the test to figure out how many points the standard deviation is for that particular test.

Raw Score: This is an often unintelligible number that tells you very little about how your students scored. Raw scores do not indicate percentiles, and they do not tell you how many questions your students answered correctly. It is actually the transformation of these raw scores into stanines, percentiles, and other related groups that make it easier to interpret the test scores. My advice is not to pay too much attention to raw scores.

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