PSY 4550 Week 2 Assignment 2 Reliability and Validity
Overview of Reliability and Validity
Outside of statistical research, reliability and validity are used interchangeably. For research and testing, there are subtle differences. Reliability implies consistency: if you take the ACT five times, you should get roughly the same results every time. A test is valid if it measures what it’s supposed to.
Tests that are valid are also reliable. The ACT is valid (and reliable) because it measures what a student learned in high school. However, tests that are reliable aren’t always valid. For example, let’s say your thermometer was a degree off. It would be reliable (giving you the same results each time) but not valid (because the thermometer wasn’t recording the correct temperature).
What is Reliability?
Reliability is a measure of the stability or consistency of test scores. You can also think of it as the ability for a test or research findings to be repeatable. For example, a medical thermometer is a reliable tool that would measure the correct temperature each time it is used. In the same way, a reliable math test will accurately measure mathematical knowledge for every student who takes it and reliable research findings can be replicated over and over.
Of course, it’s not quite as simple as saying you think a test is reliable. There are many statistical tools you can use to measure reliability. For example:
Kuder-Richardson 20: a measure of internal reliability for a binary test (i.e. one with right or wrong answers).
Cronbach’s alpha: measures internal reliability for tests with multiple possible answers.
Internal vs. External Reliability
Internal reliability, or internal consistency, is a measure of how well your test is actually measuring what you want it to measure. External reliability means that your test or measure can be generalized beyond what you’re using it for. For example, a claim that individual tutoring improves test scores should apply to more than one subject (e.g. to English as well as math). A test for depression should be able to detect depression in different age groups, for people in different socio-economic statuses, or introverts.
One specific type is parallel forms reliability, where two equivalent tests are given to students a short time apart. If the forms are parallel, then the tests produce the same observed results.
The Reliability Coefficient
A reliability coefficient is a measure of how well a test measures achievement. It is the proportion of variance in observed scores (i.e. scores on the test) attributable to true scores (the theoretical “real” score that a person would get if a perfect test existed).
Discussion Questions (DQ)
• Initial responses to the DQ should address all components of the questions asked, include a minimum of one scholarly source, and be at least 250 words.
• Successful responses are substantive (i.e., add something new to the discussion, engage others in the discussion, well-developed idea) and include at least one scholarly source.
• One or two sentence responses, simple statements of agreement or “good post,” and responses that are off-topic will not count as substantive. Substantive responses should be at least 150 words.
• I encourage you to incorporate the readings from the week (as applicable) into your responses.
• Your initial responses to the mandatory DQ do not count toward participation and are graded separately.
• In addition to the DQ responses, you must post at least one reply to peers (or me) on three separate days, for a total of three replies.
• Participation posts do not require a scholarly source/citation (unless you cite someone else’s work).
• Part of your weekly participation includes viewing the weekly announcement and attesting to watching it in the comments. These announcements are made to ensure you understand everything that is due during the week.
APA Format and Writing Quality
• Familiarize yourself with APA format and practice using it correctly. It is used for most writing assignments for your degree. Visit the Writing Center in the Student Success Center, under the Resources tab in LoudCloud for APA paper templates, citation examples, tips, etc. Points will be deducted for poor use of APA format or absence of APA format (if required).
• Cite all sources of information! When in doubt, cite the source. Paraphrasing also requires a citation.
• I highly recommend using the APA Publication Manual, 6th edition.
Use of Direct Quotes
• I discourage overutilization of direct quotes in DQs and assignments at the Masters’ level and deduct points accordingly.
• As Masters’ level students, it is important that you be able to critically analyze and interpret information from journal articles and other resources. Simply restating someone else’s words does not demonstrate an understanding of the content or critical analysis of the content.
• It is best to paraphrase content and cite your source.
• For assignments that need to be submitted to LopesWrite, please be sure you have received your report and Similarity Index (SI) percentage BEFORE you do a “final submit” to me.
• Once you have received your report, please review it. This report will show you grammatical, punctuation, and spelling errors that can easily be fixed. Take the extra few minutes to review instead of getting counted off for these mistakes.
• Review your similarities. Did you forget to cite something? Did you not paraphrase well enough? Is your paper made up of someone else’s thoughts more than your own?
• Visit the Writing Center in the Student Success Center, under the Resources tab in LoudCloud for tips on improving your paper and SI score.
• The university’s policy on late assignments is 10% penalty PER DAY LATE. This also applies to late DQ replies.
• Please communicate with me if you anticipate having to submit an assignment late. I am happy to be flexible, with advance notice. We may be able to work out an extension based on extenuating circumstances.
• If you do not communicate with me before submitting an assignment late, the GCU late policy will be in effect.
• I do not accept assignments that are two or more weeks late unless we have worked out an extension.
• As per policy, no assignments are accepted after the last day of class. Any assignment submitted after midnight on the last day of class will not be accepted for grading.
• Communication is so very important. There are multiple ways to communicate with me:
o Questions to Instructor Forum: This is a great place to ask course content or assignment questions. If you have a question, there is a good chance one of your peers does as well. This is a public forum for the class.
o Individual Forum: This is a private forum to ask me questions or send me messages. This will be checked at least once every 24 hours.