Description
After reading chapters 15,17 answer the next question.Which level of measurement would you prefer to utilize for quantitative research? Defend your answer.
Unformatted Attachment Preview
Chapter 15
Measurement and Data Quality
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #1
❖Tell whether the following statement is true or false:
❖Measurement involves assigning numbers to objects
to represent the amount of an attribute.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #1
❖True
❖Measurement involves assigning numbers to objects
to represent the amount of an attribute, using a
specified set of rules. Researchers strive to develop
or use measurements whose rules are isomorphic
with reality.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Measurement
❖The assignment of numbers to represent the
amount of an attribute present in an object or
person, using specific rules
❖Rules are necessary to promote consistency and
interpretability
❖Advantages
o Removes guesswork
o Provides precise information
o Less vague than words
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Theories of Measurement
❖Psychometrics is a branch of psychology concerned
with the theory and methods of psychological
measurement.
o Two theories
▪
Classical test theory (CTT)
▪
Item response theory (IRT)
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Errors of Measurement
❖Obtained score = True score + Error
❖Obtained score: an actual data value for a
participant
❖True score: value that would be obtained for a
hypothetical perfect measure attribute
❖Error of measurement: represents measurement
inaccuracies
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Factors That Contribute to Errors of
Measurement
❖Situational contaminants
❖Transitory personal factors
❖Response-set biases
❖Administration variations
❖Instrument clarity
❖Item sampling
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Major Types of Measures
❖Generic
❖Specific
❖Static
❖Adaptive
❖Reflective scales
❖Formative indexes
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Measurement Taxonomy
❖Four measurement property domains
o Cross-sectional domains
▪
Reliability
▪
Validity
o Longitudinal measurement domains
▪
Reliability of change scores
▪
Responsiveness
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Measurement and Statistics
❖Correlation coefficients
❖Correlation coefficients indicate direction and
magnitude of relationships between variables.
o Pearson’s r
❖Range:
o From −1.00
(perfect negative correlation)
o Through 0.00
(no correlation)
o To +1.00
(perfect positive correlation)
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Reliability #1
❖Consistency—the absence of variation in measuring
a stable attribute for an individual
❖Reliability assessments involve computing a
reliability coefficient
o Most reliability coefficients are based on
correlation coefficients.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #2
❖Tell whether the following statement is true or false:
❖Reliability coefficients usually range from .00 to
1.00, with higher values reflecting less reliability.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #2
❖False
❖Reliability coefficients usually range from .00 to
1.00, with higher values reflecting greater reliability,
not less reliability.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Reliability #2
❖Replication approaches
o Test–retest reliability: administration of the
same measure to the same people on two
occasions
o Interrater reliability: measurements by two or
more observers or raters using the same
instrument or measurements by the same
observer or rater on two or more occasions
o Parallel test reliability: measurements of the
same attribute using alternate versions of the
same instrument, with the same people
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Reliability Coefficient (R)
❖Represent the proportion of true variability to
obtained variability:
R=
VT
Vo
❖Should be at least .70; .80 preferable
❖Can be improved by making instrument longer
(adding items)
❖Are lower in homogeneous than in heterogeneous
samples
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Internal Consistency
❖The extent to which all the instrument’s items are
measuring the same attribute
❖Evaluated by administering the instrument on one
occasion
❖Appropriate for most multi-item instruments
❖Most widely used evaluation method is the
coefficient alpha
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Measurement Error
❖Unless a reliability coefficient is 1.0 (virtually never
happens), measurement error is present.
❖Used to estimate the range within which the true
score lies
o Standard error of measurement (SEM)
o Limits of agreement (LOA)
❖Measurement error is routinely estimated for multiitem measures developed with item response theory
(IRT) methods.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Validity
❖The degree to which an instrument measures what
it is supposed to measure (resilience)
❖Four aspects of validity
o Face validity
o Content validity
o Criterion-related validity
o Construct validity
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Face Validity
❖Refers to whether the instrument looks as though it
is measuring the appropriate construct
❖Based on judgment, no objective criteria for
assessment
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Content Validity
❖The degree to which an instrument has an
appropriate sample of items for the construct being
measured
o Relevance
o Comprehensiveness
o Balance
❖Evaluated by expert evaluation, via the content
validity index (CVI)
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Criterion Validity #1
❖The degree to which the instrument correlates with
an external criterion or “gold standard”
❖Focal measures
o Expense, efficiency, risk and discomfort,
criterion unavailable, and prediction
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Criterion Validity #2
❖Two types of criterion-related validity
❖Predictive validity: the instrument’s ability to
distinguish people whose performance differs on a
future criterion
❖Concurrent validity: the instrument’s ability to
distinguish individuals who differ on a present
criterion
o Specificity, sensitivity
o Predictive values
o Likelihood ratios
o Receiver operating characteristic curve (ROC
curve), area under the curve (AUC)
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Construct Validity
❖Concerned with the questions
❖What is this instrument really measuring?
❖Does it adequately measure the construct of
interest?
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Methods of Assessing Construct Validity
❖Hypothesis-testing validity
❖Convergent validity
❖Known-groups validity
❖Divergent validity (discriminant validity)
❖Multitrait–multimethod matrix method (MTMM)
❖Structural validity
❖Cross-cultural validity
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Reliability of Change Scores
❖Change score: represents the amount of change
between two scores
❖Difference score: the difference between the
randomized groups at posttest
❖Smallest detectable change (SDC): a change in
scores that is beyond measurement error
❖Reliable change index (RCI): assesses the clinical
significance of improvement during a
psychotherapeutic intervention
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Responsiveness
❖The ability of a measure to detect change over time
in a construct that has changed, commensurate with
the amount of change that has occurred
❖Whether a change score is truly capturing a real
change in the construct
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #3
❖Tell whether the following statement is true or false:
❖Reliability is the degree to which an instrument
measures what it is supposed to measure.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #3
❖False
❖Validity is the degree to which an instrument
measures what it is supposed to measure. Reliability
is the degree of consistency or accuracy with which
an instrument measures an attribute.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Critiquing Data Quality in Quantitative
Studies
❖Can I trust the data in this study?
❖Are the measurements of key constructs reliable and
valid, and are change scores reliable and
responsive?
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Psychometric Assessment
❖Gather evidence
o Validity
o Reliability
o Other assessment criteria
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 17
Descriptive Statistics
Copyright © 2017 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #1
❖Tell whether the following statement is true or false:
❖Nominal measurement is the ranking of objects
based on their relative standing on an attribute.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #1
❖False
❖Nominal measurement: the classification of
characteristics into mutually exclusive categories
❖Ordinal measurement: the ranking of objects based
on their relative standing on an attribute
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Levels of Measurement
❖Nominal measurement: the classification of
characteristics into mutually exclusive categories
❖Ordinal measurement: the ranking of objects
based on their relative standing on an attribute
❖Interval measurement: indicating not only the
ranking of objects but also the amount of distance
between them
❖Ratio measurement: distinguished from interval
measurement by having a rational zero point
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #2
❖Tell whether the following statement is true or false:
❖Frequency distributions impose order on raw data.
Numeric values are ordered from lowest to highest,
accompanied by a count of the number of times
each value was obtained.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #2
❖True
❖Frequency distributions impose order on raw data.
Numeric values are ordered from lowest to highest,
accompanied by a count of the number (or
percentage) of times each value was obtained.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Frequency Distributions
❖ Impose order on raw data
❖ Numeric values are ordered from lowest to highest,
accompanied by a count of the number (or percentage) of
times each value was obtained
❖ Three characteristics
o Values
o Central tendency
o Variability
❖ Common methods of display
o Histograms
o Frequency polygons
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Shapes of Distribution
❖ Symmetric: two halves are mirror images of each other
❖ Skewed: asymmetric with one tail longer than the other
o Positively skewed
o Negatively skewed
❖ Modality: number of peaks
o Unimodal
o Bimodal
o Multimodal
❖ Normal distribution
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #3
❖What is the median?
A. Average or typical value of a set of scores
B. Value that occurs most frequently in a distribution
C. Point above which and below which 50% of the
cases fall
D. Arithmetic average of all scores
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #3
❖C
❖Central tendency are indexes, expressed as a single
number, that represent the average or typical value
of a set of scores. The mode is the value that occurs
most frequently in a distribution; the median is the
point above which and below which 50% of the
cases fall; and the mean is the arithmetic average of
all scores.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Central Tendency
❖Central tendency are indexes, expressed as a single
number, that represent the average or typical value
of a set of scores
❖Mode: value that occurs most frequently in a
distribution
❖Median: point above which and below which 50% of
the cases fall
❖Mean: arithmetic average of all scores
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question #4
❖Tell whether the following statement is true or false:
❖Range is the distance between the highest and
lowest scores.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer to Question #4
❖True
❖Range is the distance between the highest and
lowest scores.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Variability
❖Variability: how spread out the data are
❖Range: distance between the highest and lowest
scores
❖Standard deviation: indicates how much, on
average, scores deviate from the mean
❖Calculation
o Deviation scores represent the degree to which
each person’s score deviates from the mean.
The variance is equal to the SD squared.
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Bivariate Descriptive Statistics
❖Relationships between two variables shown in
crosstab tables
❖Contingency table is a two-dimensional frequency
distribution in which the frequencies of two nominalor ordinal-level variables are crosstabulated
❖Correlation coefficients describe the direction and
magnitude of a relationship between two variables
o Product–moment correlation coefficient
(Pearson’s r)—interval or ratio
o Spearman’s rho coefficient—ordinal
❖Scatter plot
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Risk Indexes #1
❖Absolute risk reduction: expresses the estimated
proportion of people who would be spared from an
adverse outcome through exposure to an
intervention
❖Relative risk: estimated proportion of the original
risk of an adverse outcome that persists among
people exposed to an intervention
❖Relative risk reduction: estimated proportion of
untreated risk that is reduced through exposure to
the intervention
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Risk Indexes #2
❖Odds ratio: ratio of the odds for the treated versus
untreated group
❖Number needed to treat: estimate of how many
people would need to receive the intervention to
prevent one adverse outcome
Copyright © 2021 Wolters Kluwer Health | Lippincott Williams & Wilkins
Purchase answer to see full
attachment
