Chapter 2 Validity, Reliability, and Objectivity
What are four ways to maximize validity?
1. Select measures who are not associated in any way with the outcome of the measurement (e.g. coaches are terrible judges when their own teams compete). 2. Devise clear, complete directions for scoring (i.e. define terms and assign score values). 3. Train the measurers thoroughly so that all understand exactly what should be done and so that they have adequate experience doing it. 4. Monitor scoring and scorers for evidence of bias.
Reliability largely depends on what three factors?
1. The validity of the score 2. The repetition of the measurement (the more a measure is repeated, the better the reliability) 3. The stability of the measured characteristic
What three factors largely determine objectivity?
1. The validity of the score. 2. The availability of good, clear directions for administering the measurement. 3. The ability and willingness of measurer to read, understand, and follow directions precisely.
What are some of the ways to maximize objectivity?
1. Use a well-designed test that measures the exact quality you want to measure. 2. Administer the test carefully. 3. Anticipate and eliminate external factors that may affect the score. 4.Develop a clear set of directions. 5. Describe measurement criteria clearly. 6. Use various strategies to make everything as objective as possible.
Measurements that are more valid are usually more what?
Are usually more expensive, take longer, require more equipment, or require more personnel than less valid measures.
Define reliability.
Dependability, consistency, or repeatability; a measurement can be repeated over and over, with similar results each time.
Some factors that negatively affect reliability are?
Fatigue because if you make me run 3 miles, then ask me to do it again with no rest. I might be able to give you a reliable result.
How do reliability and validity relate?
If the reliability of a measurement is very good, we sometimes accept that as a rough indicator of the measurement's validity. It is not a guarantee of validity. Validity requires a small amount of error, so a large consistent error means that the measurement is not valid, even though it yields good reliability.
What is an interval measure?
Interval (arbitrary zero and cannot compare values as ratios)
Continuous measures come in two types. What are they?
Interval measures and ratio measures.
Objectivity only does what?
It only minimizes the error arising from the measurer.
Good measurement techniques will yield what?
More valid, reliable, and objective measurements.
What is a ratio measure?
Ratio (has an absolute zero and can compare values as ratios)
What are examples of ratio measure?
Ratio measures would include such things as respiration rate, heart rate, height, weight, speed, etc.
Define objectivity.
Reliability between different raters or judges; the degree to which a measurement is free from bias.
What is an example of interval measure?
Temperature scales are an example of an interval measure (something that is 32 degrees is NOT half as cold as something that is 64 degrees).
What is an example of intra-reliability?
Testing within yourself such as stopping a stopwatch at a certain time.
Define validity.
The degree to which a measurement measures what it is supposed to measure, with acceptable error.
What is a regression to the mean?
The tendency for extreme scores to move toward the average the second time a test is taken.
Express validity.
Valid X = T + acceptable E where X is the measurement, T is the true score, and E is the error
What is the most important characteristic that any measurement could have?
Validity.
What is the primary goal in a measurement?
Validity.
Express the measurement equation in a variable format?
X = T + E measurement = true value + (can be positive or negative) error.
Express objectivity.
X with good objectivity = T ± acceptable E due to the measurer (where x represents the score, T is the true score, and E is the error)
What are the two parts to a measurement equation?
measurement = true value + or - some error
