Exam 2 Quantitative Measurement Flashcards
Where is data collection found?
Methods section of the article.
Rule of thumb
“Garbage in, garbage out” If you make poor measurements, you’re going to get bad results
Pretest tools. Why?
Performs as expected
Ease of administration
Time commitment
Subject understanding
Data/datum
Data is plural, datum singular
Instrument/tools
Different word, same thing
Remote indicator
how to measure something.
Example: A way to measure pain…facial expression, body language
Standardized instrument
An instrument (or tool) that has been checked for reliability/validity, always will work the same
Subscale
Take a general topic, break it down
Explicit
As accurate as possible
Widely applicable
Applies to the general population
Orderly
Tidy flow…visually aesthetic
Specific
Specific to topic…
Example: DEPRESSION, not anxiety or sadness
Realistic
Time appropriate, cost appropriate
Structure
High(forces subject to pick a specific answer), middle, low(open ended questions)
Quantifiability
Ability of data to be recorded by numbers
Obtrusiveness
To what extend does the subject know they are being observed/assessed
Objectivity
To what extend are the results subject to bias
Descriptive/Exploratory Design
Observational checklist - unique to this design
Questionnaire - very popular
Scale
Correlational/Quasi-Experimental/Experimental/Clinical Trial
Questionnaire
Survey
Biophysical
Biophysical Measurement…why use?
Relevance to nursing (BP, HR, Temp, Lab values…etc)
Impact of nursing actions
Evaluate nursing procedures
Find health related correlations
Biophysical Measurements need to be…
Appropriately collected, recorded, stored, tested, and reported
Psychosocial Measurements
Self Reports
Interviews, written questionnaires, etc
Psychosocial Measurements
Observations
Checklists, observational rating scales
Likert-type
5-7 points
Ex: strongly agree, agree, undecided, disagree, strongly disagree
Visual Analog Scale (VAS)
0-100mm
100mm line, subject places vertical line on scale based on their answer.
Semantic differential
Forced choices, range
Ex: range of sad to happy, five blank lines, place check mark saying how happy you feel.
Q-sort
agree/disagree
Sort index cards into piles…agree/disagree, then agree/strongly agree; strongly disagree/disagree
Projective techniques
Appropriate for right brained people/children
Ex: Ink blots, pictures, music. Opinions are projected on the image
Criteria when examining tools
Appropriate (to question/design/population)
Feasible
Acceptable to subject
Reliable and valid
Measurement Errors
Need to reflect as much truth as possible in our measurements
Observed value
True value + Error
Error can be:
Random Systematic (Biased)
How can you reduce error?
Use reliable and valid tools.
Reliability
Examines stability, equivalence and internal consistency of the tool
Correlations
-Pearson r
Chronbach’s alpha
.90 and above is very reliable
.80-.89 very good
.60-.79 typical
Stability:
-Test/retest
same instrument given more than one time using same conditions
find if there is a correlation (r) between scores
want a strong correlation
Stability:
-parallel/alternate form
two versions of the same instrument
Example: use the same questions, but move them around…put them in a different order
Internal consistancy
The questionnaire deals with the same conceptual area consistently throughout the tool
ex: all the questions are about “happiness”
Split-half
see if 1st half and 2nd half of test are highly correlated
item to total
strong correlation in total score
kuder-richardson coefficient
dichotomous scores
chronbach’s alpha
continuous scores
Equivalence
-Inter-rater
Do two or more people score the observations the same
Gives the researcher a correlation coefficient
If doing the test-retest…
the longer the lag time, the lower the r
The more homogeneous the sample…
they lower the reliability.
Validity
The tool actually measures the variable of interest.
Can a tool be valid without being reliable?
NO. If a tool is valid, it must be reliable. However, a tool can be reliable without being valid.
Face
The items (questions) look appropriate to the general population. It “looks right.”
Content
Items derived from literature and expert advice.
Items look appropriate to experts in the field
Items with questionable ratings are modified or dropped.
Construct
Do the items measure all important aspects of the concept and are those important aspects measured appropriately.
- Known groups
- Hypothesis testing
- Convergence/divergence
- Factor analysis
- Multimethod/multitrait
Criterion
Compares to another measure…logically connected
-Tries to determine how observed score might compare to the true scores
Predictive
This measurement correlates well with predictions made using this measurement.
Ex. if you have a strong high school GPA, you’ll have a strong college GPA
Concurrent
This measurement correlates well with another ‘gold standard’ measurement given at the same time.
Sensitivity
The ability of an instrument to correctly identify a “case” or correctly screen for or diagnose a condition.
Ex. This IS depression
Specificity
The ability of an instrument to correctly identify ‘non-cases’ or to rule out those without the condition.
Ex…this shows it is NOT depression
Response rate
Very low… 5%, 10% with a reminder
Subject characteristics
may limit responses…age, physical limitations
Complexity
Needs to be low in complexity in order to be comprehended
Scale
specifies all the possible values a given measurement may have
All scales have:
- At least two values
- Exhaustive scope
- Mutually exclusive categories
Categorical/dichotomous
1 for boy, 2 for girl
Continuous
1,2,3,4 etc…
Nominal
Using an arbitrary number represent your variable
ex. 1 for boy, 2 for girl
* Categorical
Ordinal
Using a systematic ordering of numbers to represent ordered responses.
Not measured…no ‘distance’ between numbers.
Ex. Strongly agree=5….strongly disagree=1
*Categorical
*Likert-scale
Interval
Using a systematic ordering of numbers to represent ordered responses
there IS a true distance between the numbers
NO true zero point
*Continuous
ex. temperature (above and below zero)
Ratio
Most sophisticated There is a true distance between the numbers IS a true zero point *Continuous Ex height/weight/age
Scoring the tool
Check the instructions
Total scores vs. subscale scores
Positives and negatives…today was a good day yes or no, vs, today was a bad day yes or no
