### Calculating And Understanding T-Tests Research Paper

Length: 4 pages Sources: 1 Subject: Teaching Type: Research Paper Paper: #17214699 Related Topics: Reliability, Math, Norms, Testing
##### Excerpt from Research Paper :

Testing and Assessment

Describe the basic characteristics of a standardized test and norms.

Standardized tests are administered and scored in a consistent manner. When standardized tests are given, conditions are held consistent and conducted in a predetermined way that is considered the standard for the test. Some of the variables that are held constant include, such as the test questions, the conditions for administering the tests, the scoring procedures and interpretations of the answers. Norms are generated by using a single test score to relate it to the test scores of other students, or by the same students at different times. Norms are generally established on a nation-wide basis on standardized tests rather than classroom tests that are made by teachers.

A test measuring basic math skills in adults is normally distributed, with mean = 20 and standard deviation = 7.

Calculate the z score and T score for each of the following test scores:

The formula for computing z-scores is:

Raw Scores

Z Scores

11

-1.29

Score is less than the mean by more than1 standard deviation

18

-0.29

Score is less than the mean by about 1/4 standard deviation

24

0.57

Score is more than the mean, by about 1/2 standard deviation

32

1.71

Score is more than the mean by more than1 standard deviation

This means the formula for computing standard scores is:

Or this more complex formula: t = [ x - ? ] / [ s / sqrt ( n ) ]

Raw Scores

Z Scores

T Scores

11

-1.29

-1.46

18

-0.29

-0.46

24

0.57

0.39

32

1.71

1.54

What is the usefulness of transforming raw scores to z scores or T scores? What do these numbers tell us?

Converting individual raw scores into a standardized form provides a more meaningful description of the individual scores that make up the distribution. Z scores are a conversion of individual raw scores into a standardized form that relies on the population mean and standard deviation. T scores -- also known as standardized scores -- are a conversion of individual raw scores into a standard form, and the transformation is made without knowledge of the validity that apply to tests.

Types of Reliability.

In research, reliability means repeatability or consistency. As long as what is being measured does not change, a reliable measurement will produce the same result or outcome over and over again, as long as what is being measured does not change. A dependable measure has both validity and reliability. Reliability is an informed estimation and these estimations fall into four categories that look at reliability in a different way. 1) Inter-rater or inter-observer reliability is used to determine the consistency of several raters over time when they are observing the same thing and scoring what they observe. 2) Test-Retest Reliability - This estimate is used to determine some measure of consistency from one time to another time, again, by scoring or rating…

###### Sources Used in Documents:

Reference

Aiken, L.R. And Groth-Marnat, G. (2006). Psychological testing and assessment (12th ed.). Boston, MA: Allyn & Bacon.

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