53 terms

research: measurments (feel free to edit this set!)

this set can be edited by anyone so feel free to add to or take away
Consists of rules for assignment number
of objects to represent quantities of attributes
Process of assigning numbers to variables
measurement rules x 3
under what conditions, what method, numeric values to be used
advantages to measurement x4
removes guess work from gathering info, can be independently verified by others (objectivity), produce precise info, language of communication
errors of measurement
instrument not accurate= degree of error
obtained score=
true score +/- error
these are problematic because they represent an unknown quantity and they are variable
errors of measurement
what contributes to errors of measurement
situational contaminants, transitory personal factors, response-set biases, Instrument format, Administration variations, Instrument clarity, Item sampling-errors
scores can be affected by the conditions under which they are produced
situational contaminants
scores of an individual
may be influenced by temporary personal states
transitory personal factors
number of relatively enduring
characteristics of the respondents that can interfere
with accurate measures of the target attribute.
response-set biases
alterations in the methods of collecting data from one subject to the next
administrative variations
if directions for obtaining measures are vague or poorly
understood, then scores may be affected
Instrument clarity
sometimes introduced as a result of the sampling of items used to measure an attribute
Item sampling-errors
technical characteristics of an instrument can influence the obtained measurement
Instrument format (example: open ended questions vs closed ended questions)
The degree of consistency with which an instrument measures the attribute it is
supposed to be measuring
characteristics of reliability x 3
stability, consistency,
dependability of a measuring tool
the less variation an instrument produces...
the higher its reliability
extent to which same results are obtained on repeated administrations of the
administration of the same
test to a sample of individuals on two occasions
then compare the scores obtained
• Compute a reliability coefficient
Test-retest procedure
Looks for a relationship between two phenomena
Reliability coefficient
advantages of reliability x 3
- Test-retest method is easy
- Can be used with self- report, observational & physiologic
- Used with traits that are relatively enduring such as personality,
abilities or physical attributes such as height
disadvantages of reliability
- Many traits do change over time- regardless of the measure eg
(behaviors, attitudes etc)
- Second administration may be influenced by memory of first
- Subjects may change as a result of taking the test the first time
- Responses could be haphazard if subject is bored or impatient
with instrument
correlation of various items
within the instrument (homogeneity), measures the
same characteristic, Most widely used method for reliability, Requires only one test administration
Internal Consistency
- The items composing a test are split into two groups and scored independently
- Score on the two half-tests are used to compute a correlation coefficient
Split-half technique
advantages of Split-half technique
Easy to use, Eliminates most of disadvantages of test-retest
disadvantages of split-half technique
Reliability estimates can be obtained by using different splits (odd/even; first/second half)
Produce a reliability coefficient that can be interpreted as the other correlation coefficients, Yields values of 0 to 1.0
Chronbach's alpha or Kuder-Richardson
20 (KR 20)
why is Chronbach's alpha or Kuder-Richardson better than split-half technique
because it computes all possible splits to estimate homogeneity
Comparing two versions of same instrument or two observers (inter-rater reliability) measuring the same event
what is the goal of equivalence
Goal is to determine the consistency or equivalence of the instruments in yielding
measurements of the same traits in the same people
is estimated by having two
or more trained observers watching some event
simultaneously & independently recording the
relevant variables according to a predetermined
plan or coding system
Interrater reliability
how are the results of the Interrater reliability used?
Results are used to compute an index of equivalence or agreement. Can use a correlation coefficient to compare results
* Refers to the degree to which an instrument measures what it is supposed to be measuring.
(Accuracy of the measure)
o Whether the instrument looks as though it is measuring the appropriate critical variable (or construct).
o Not the strongest way to determine validity
Face Validity
o How well the instrument represents the characteristic to be assessed
o Used for affective measures (feeling, emotions, psychological traits) & cognitive measures (knowledge)
o Based on judgment of experts
Content Validity
o Must ask the question: "how representative are the questions on this test of the universe of all questions that might be asked on this topic?"
* Cognitive Scale
Emphasis is on establishing the relationship between the instrument and some other criteria, Criterion must be clear cut & objective
Criterion-Related validity
Criterion-Related validity examples
* For example: instrument to measure birth control use among sexually active teenage girls-criterion to compare it to may be subsequent premarital pregnancy
* Measure professionalism among nurses (attribute to be measured) to number of articles published (criterion)
* Measure effectiveness of nursing care to supervisory ratings of nurse
true or false: Criterion related validity is a relationship but also is a predictive relationship
o Degree to which an instrument can accurately forecast the future
Predictive validity
o Judgment is to the degree to which an instrument can accurately identify a difference in the present
o Use 2 instruments to measure the same concept
Concurrent validity
Method for indentifying clusters of related variables.
Procedure is used to identify and group together different measures of some underlying attribute
* Factor Analysis
each cluster is called a factor, what does this represent
* Represents a group of items that identify the same characteristic
true or false: Validity is never proven
true: its verified, supported by evidence
T or F: reliability and validity Are not totally independent qualities
T or F: A measuring device that is valid must be reliable
T or F: An instrument can be reliable without being valid
Beliefs that are held to be true but have not necessarily been proven OR A principle that is accepted as being true based on logic or reason, without proof
beliefs assumed to be true by a large percentage of society (all humans need love)
universal assumption
characteristics of assumptions
Derived from a theory of previous research (stress causes disease).
Specific to a certain research study (evidence of a fit between what the researcher believes can happen & the data produced)
T or F: Assumptions ARE NOT THE research question or hypothesis
Uncontrolled variables that may affect study results and limit the generalizability of the findings
• Limitations mentioned could include x3
* Sample deficiencies
* Design flaws
* Weaknesses in data collection