Ch18Research Flashcards
What is the definition of measurement used by the text?
systematic process by which things are differentiated; not a random process, but proceeds according to rules and guidelines
What are some of the examples of variable properties?
distance, duration, frequency, magnitude, topography, latency, pattern
What are the scales of measurement?
Nominal, Ordinal, Interval, Ratio
What are nominal scales?
classification without placing any value on the categories; none of the properties of a real number system; identified by name or numeral
ex: quadriplegic, dipelgic, and hemiplegic
What are ordinal scales?
indicate whether a person or object has more or less of a certain quality; do not ensure that there are equal intervals between categories or ranks; possesses one property of a real number system (order)
Ex-the amount of assistance a patient needs to ambulate is often rated as maximal, moderate, minimal, standby, or independent.
What are interval scales?
have order and distance, but lack origin; equal intervals so addition and subtraction are meaningful, but because there is no meaningful zero, multiplication and division are not useful.
ex: Celsius and Fahrenheit temperature scales
What are ratio scales?
exhibit order, distance, and origin; all arithmetic functions can be applied; absence is zero
ex: Length, time and weight are generally considered ratio scales because their absence is scored as zero, and the intervals between numbers are known to be equal.
How do you determine the scale of a measurement?
determine whether there is a true zero (origin), whether intervals between numbers are equal (distance), and whether there is an order to the numbers or names that constitute the measure (order)
What are the two classifications of variables?
continuous and discrete
What are continuous variables?
one that theoretically can be measured to a finer and finer degree
ex- time (seconds then milliseconds, etc)
What are discrete variables?
numbers can only assume only distinct values, no “between categories”
ex - male/female, quadriplegic/dipelgic/hemiplegic
What seven basic concepts underlie measurement theory?
1 frequency distribution, 2 mean, 3 variance, 4 standard deviation, 5 normal curve, 6 correlation coefficient, and 7 standard error of measurement
What are the two basic frameworks in which measurement is conducted and evaluated?
norm-referenced and criterion referenced
What are norm-referenced frameworks?
Judge individual performance in relation to group norms
What are criterion referenced frameworks?
individual’s performance is evaluated with respect to some absolute level of achievement
How is reliability defined?
the degree to which test scores are free from errors of measurement
What are the two theories of reliability?
classical measurement theory and generalizability theory
What is classical measurement theory?
the assumption that every measurement, or obtained score, consists of a true component and an error component
What is generalizability theory?
recognizes that there are different sources of variability for any measure