Discussion: Test-Retest Reliability
Discussion: Test-Retest Reliability
Sexual Assault
Question(s): be prepared to discuss (2 questions)
1. Please mention at least ten characteristics and/or indicators that a child may have been sexually abused (50 points – 5 points each characteristics and/or indicators)
2. Choose one and discuss/develop (50 points)
Guidelines:The answer should be based on the knowledge obtained from reading the book, no just your opinion. If there are 2 questions in the discussion, you must answer both of them. Your grade will be an average of both questions.
Reading Reflection Chapter 9
“Reliability”
Please submit minimum of 250 word statement (APA style) with references (2) regarding this week chapter reading, explain what are some of the important aspects of this week’s reading, provide examples when possible.
Power point with chapter 9 added.
Measurement is the assignment of number to object or events according to certain rules (Carmines and Zeller, 1979)
Measurement
Measurement is important in quantitative research because:
Quantification allows for powerful statistical analysis
Numbers are often more clearly communicated
Objectivity is increased
Efficiency may be increased
Levels of Measurement
Nominal: a label but nothing more
Categorical: identifies group membership
Ordinal: indicates an order
Interval: also in order but an estimation of distance between the scores
Ratio: order, defined distance, and a zero point
Measurement Error
The sources of error causing unreliability may be one or more of the following:
Measurement is inaccurate or inconsistent
Raters or testers are inaccurate or inconsistent
Measurement Error
The sources of error causing unreliability may be one or more of the following:
Phenomenon being measured varies from one measurement time to the next
The situation is confounding the measurement
Classic Measurement Equation
A type of reliability that is evaluated by administering the same test to the same people or taking the same measurement on the same people after a specified period of time
The results of the two testing times are then compared statistically
Test-Retest Reliability
Factors affecting the test-retest reliability:
Assumes stability in the phenomenon being measured
May be affected by reactivity
Practice effect may also affect reliability
Test-Retest Reliability
Ways to calculate test-retest reliability include:
Pearson product moment correlation
Intraclass correlations (ICCs)
Homogeneity
Cronbach’s alpha can be used to test the homogeneity of items within a measure
It indicates the extent to which all of the items on the test are “behaving” similarly
Homogeneity
Alpha of 0.70 is acceptable for new measures
Alpha of at least 0.80 is expected for established measures
Higher alphas (at least 0.90 or higher) are desirable for use in clinical evaluation
Reliability of Physical Measures
Systematic error: a consistent error
Random error: inconsistent, unpredictable errors
Random errors can cancel each other out unless the researcher know how to detect them by using the technical error of measurement (TEM)
√ ∑ d2 d = the difference between scores of paired examiners
You must proofread your paper. But do not strictly rely on your computer’s spell-checker and grammar-checker; failure to do so indicates a lack of effort on your part and you can expect your grade to suffer accordingly. Papers with numerous misspelled words and grammatical mistakes will be penalized. Read over your paper – in silence and then aloud – before handing it in and make corrections as necessary. Often it is advantageous to have a friend proofread your paper for obvious errors. Handwritten corrections are preferable to uncorrected mistakes.
Use a standard 10 to 12 point (10 to 12 characters per inch) typeface. Smaller or compressed type and papers with small margins or single-spacing are hard to read. It is better to let your essay run over the recommended number of pages than to try to compress it into fewer pages.
Likewise, large type, large margins, large indentations, triple-spacing, increased leading (space between lines), increased kerning (space between letters), and any other such attempts at “padding” to increase the length of a paper are unacceptable, wasteful of trees, and will not fool your professor.
The paper must be neatly formatted, double-spaced with a one-inch margin on the top, bottom, and sides of each page. When submitting hard copy, be sure to use white paper and print out using dark ink. If it is hard to read your essay, it will also be hard to follow your argument.
