Exam 2 Flashcards

1
Q

What experimental design is not a true experiment and why?

A
  • A quasi-experimental design
  • lack randomization
  • lack comparison groups
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2
Q

What is the gold standard of true experimental design?

A

Randomized Control Trial

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3
Q

What occurs in a true experimental design?

A
  • Subjects are randomly assigned to at least 2 comparison groups
  • Experiment enables control over most threats to internal validity and provides the strongest evidence for causal relationships
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4
Q

What is a completely randomized design?

A
  • Between subject design

* Subjects assigned to groups based on a randomization process

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5
Q

What is a randomized block design?

A
  • Subjects classified according to an attribute (blocking variable)
  • Then randomized to treatment groups
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6
Q

What is a repeated-measures design?

A
  • Within-subjects design (everyone gets same interventions)

* Subject acts as own control

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7
Q

How many independent variables do single-factor designs have?

A

*One independent variable

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8
Q

How many independent variables do multi-factor designs have?

A

*Two or more independent variables

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9
Q

What is a single-factor design?

A
  • One way design
  • 1 independent variable is investigated
  • 1 or more dependent variables
  • Looking at how many independent variables there are, not how many dependent variables there are
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10
Q

What occurs with a RCT with 2 groups based on random assignment?

A
  • Pretest-posttest control groups design
  • Independent groups= treatment arms
  • Testing pre and post treatment
  • Changes in experimental group are attributable to the treatment
  • Establishes cause and effect relationship
  • Change in the experimental group is the post result minus the pre result to get the overall result. The change becomes the dependent variable
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11
Q

What occurs in a 2-group pretest posttest design?

A
  • Comparison group recieves a second form of the intervention
  • 2 experimental groups formed by random assignment
  • Control group is not feasible or ethical
  • Compares new treatment with “standard care”
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12
Q

What is a multi-group pretest posttest control group design?

A
  • Multiple intervention groups

* Includes a control group

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13
Q

What are pre-test post-test designs strong in?

A

*Strong in internal validity

*

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14
Q

How can the initial equivalence of groups be established?

A

*By pretest scores (important for inferring causality)

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15
Q

How is selection bias controlled in pretest posttest designs?

A

*Controlled because of random assignments

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16
Q

What should effect groups equally in pretest posttest designs?

A

*History, maturation, testing, instrumentation

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17
Q

How is the analysis of pretest posttest designs often done?

A
  • Often analyzed using change scores
  • difference between posttest and pretest
  • Also can use analysis of covariance (ANCOVA) to compare posttest scores
  • using pretest scores as covariate
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18
Q

What is a posttest only control group design?

A
  • Same as pre-test posttest control group design
  • EXCEPT no pre-test
  • Used when dependent variables can only be assessed following treatment
  • e.g. length of stay in hospital (see example pg 199)
  • Used when pretest is impractical or detrimental
  • Is an experimental design involving randomization and comparison groups
  • Strong internal validity
  • Assumes groups are equivalent prior to treatment
  • works best with large samples to increase probability of “equivalency”
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19
Q

What occurs in a multi-factor design for independent groups?

A
  • single factor designs have 1 independent variable (with 1 or more levels) and do not account for interactions of severable variables
  • Multi-factor designs have 2 or more independent variables
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20
Q

What occurs in a factorial design?

A
  • Factorial design incorporates two or more independent variables, with subjects randomly assigned to various combinations of levels of the two variables
  • Two-way (two-factor) design has 2 independent variables
  • Three-way (three-factor) design has 3 independent variables
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21
Q

What is a survey?

A
  • A series of questions
  • interview
  • questionnaire (written/electronic)
  • Can be used in:
  • experimental studies, exploratory studies, descriptive studies
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22
Q

What occurs in an interview?

A
  • Ask questions and record answers
  • Structured format
  • Unstructured format
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23
Q

What occurs in a structured interview?

A
  • Standard set of questions
  • Same questions in same order to all subjects
  • Same response choices
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24
Q

What occurs in an unstructured interview?

A
  • Less formal
  • Open ended
  • Conversational
  • Often used in qualitative studies
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25
What occurs in questionnaires?
* Structured surveys * Self-administered * Computerized or pen/paper * Efficient as completed on subject’s own time * Reduced bias from interactions with an interviewer * Disadvantage is the potential for misunderstanding or interpreting questions * Mail, electronic distribution * Low return rates (30-60%) limit external validity of results
26
What are data collected via interview or questionnaire based on?
* SELF REPORT! - no direct observation by the researcher of subject's behavior - potential for bias or inaccuracy - recall bias
27
What should be asked when making a survey design?
* Delineate the overall research question - What are the objectives (guiding questions) of the study? - These objectives focus the content of the questionnaire * Outline of the questionnaire (relate to objectives) * Review existing instruments - Can they be adapted for my study? * Write questions that address each of the objectives
28
What do you ask when you distribute your preliminary draft of survey to colleagues?
* Ask for feedback * Revise * Distribute again * Helps establish content validity of the instrument
29
What size sample should you do a pilot test on?
* Small sample of 5-10 research subjects - interview respondents for feedback - revise - retest
30
How do you select a sample for surveys?
* All PTs in Michigan | * Purchase mailing lists
31
How do you contact respondents?
* Cover letter | * Follow Up
32
What do scales of surveys provide?
*Provide rating of degree to which subject possesses a characteristic/attitude/value
33
What are the scales of surveys?
* Likert: - Strongly agree - Agree - Neutral - Disagree - Strongly disagree * Likert scales coded 1-5 * Calculate overall score by adding answers * 1 item does not carry more weight than others * *visual analog scale - Place a mark on the 100 mm line
34
What is the Delphi Technique?
* Experts complete multiple e.g. 3 rounds of questionnaires * Researcher reviews and distributes findings after each round * Eventually come to consensus on an issue - e.g. what should entry level knowledge be for a particular topic
35
How do you do an analysis of survey data?
* Code the data e.g. male 1, female 0; * Fear of falling 1, no fear 0 * SA=5; A=4; N=3; D=2; SD=1
36
What does descriptive statistics do?
* Summarize responses * Mean age; years of education etc. * Categorical data - Frequency/percentages: 25 males (33% of sample) - 40% SA; 30% A; 20% Neutral etc * Scores on a scale may be summed Ex. mean ABC=84%
37
What does an IRB do?
* Must approve survey research * Protection from psychological harm * confidentiality * Informed consent must be provided by participants
38
What is the best way for clinicians to seek evidence for interventions and assessments?
* Systematic Reviews | - Cochrane Collaboration
39
What should a study question be?
* Question is very specific | * Well described purpose statement
40
What is a narrative review?
*There's a broad question to be answered with search strategies and selection of articles not usually described. Appraisal is not always rigorous and the conclusions are usually descriptive/qualitative
41
What is a systematic review like?
*The question is focused and the search strategies/databases are often described in detail. The selection of articles are rigorous based on specific criteria. Appraisal is very rigorous and the conclusion maybe qualitative or quantivative (meta-analysis)
42
What are the selection criteria of a systematic review?
* “Subjects” of the review are the studies * Specify inclusion/exclusion criteria * Based on: - Types of studies - Types of participants - Types of interventions - Types of outcome measures
43
What is the search strategy for a systematic review?
* Select keywords * Identify resources - Databases - Grey literature (unpublished studies) * Publication bias * Conduct the search and retrieve relevant papers
44
How do you evaluate quality of selected studies?
* Critical review * Record on a form * Evaluate quality of design and data analysis
45
What are the types of study bias?
* Selection bias * Performance bias * Attrition bias * Detection bias
46
What is the Jadad Rating scale?
* 3 questions * Was study randomized (1 point if yes) * Was study described as double blind (1 pt yes) * Was there a description of withdrawals and dropouts (1 pt yes)
47
How many items is the PEDro Scale?
*11 items
48
What is Data synthesis?
* Heterogeneity (dissimilarity) or homogeneity of the included studies (variability across studies) - Composition of treatment groups (inclusion/exclusion criteria) - Design of study (including length of follow up) - Management of patients (treatments provided/Presence of complications)
49
What are the analysis/synthesis of findings?
* Overall conclusions based on quality of evidence obtained | * Often summarize findings in a table
50
What is a forest plot?
* Represents the overall result of the meta-analysis - square is the outcome for that study [relative risk (RR)]; size of square relates to weighting of study based on sample size - line represents confidence interval (CI) around the RR - diamond is combined overall estimate of results [includes pooled point estimate (center of diamond) and CI (horizontal tips of diamond)]
51
Describe the confidence interval (CI) of a forest plot?
*If a CI of a result crosses the line of no effect, then either a significant difference does not exist b/w the treatment and the control or the sample size was too small to show an effect
52
What is meta-analysis homogeneity?
*results of each individual trial are mathematically compatible with the results of the other trials
53
What are heterogeneous studies?
* If the CIs do not overlap; heterogeneous studies | - no common treatment effect across the studies
54
What is a two-way factorial design?
* Incorporates 2 independent variables - effect of intensity (vigorous/moderate) on exercise behavior - Effect of location (home/community center) on exercise behavior - 2x2 design means 2 independent variables and 2 levels of each independent variables (4 groups)
55
What are the two-way factorial design main effects?
* Is there an effect of moderate versus vigorous exercise * Is there an effect of exercsing at home or in community * This is examining main effect of each independent variable
56
What are two-way factorial design interactions?
* Can also examine interaction effects between 2 independent variables - Effect of 1 variable varies at different levels of the second variable - e.g. maybe moderate exercise is more effective in changing exercise behavior but only when performed at a community center
57
When is a randomized block design used?
* When there is concern that an extraneous factor such as gender might influence differences between groups - build the variable into the design as an independent variable
58
How many independent groups are in a repeated measures design?
* Up to now considered 2 independent groups | - experimental and control groups created by random assignment or by blocking
59
What is a repeated measures design?
* One group of subjects is tested under all conditions * Each subject acts as their own control * aka within-subjects design
60
What are the advantages to a repeated measures design?
* Subject differences can be controlled - Ex: differences between experimental and control groups are nullified bc no groups used - Physiological and other factors remain constant throughout the experiment - Subjects act as own controls provides most equivalent "comparison group" possible
61
What are the disadvantages of repeated measures design?
* Learning/practice effects when one person repeats measurements over and over * Carryover effects when exposed to multiple treatment conditions - Must allow enough time for dissipation of previous effects so there’s not cross-over
62
Why might repeated measures designs not be considered true experiments?
* Bc no randomized comparison groups - However if they incorporate randomization of the order of repeated treatments/interventions then can be considered experiment
63
What is a one-way repeated measures design?
*One group of subjects is exposed to all levels of one independent variable
64
What is Order Effects?
*were responses dependent on which condition preceded which other condition?
65
What is the Solution to problem of order effects?
*Randomize order of conditions/interventions for each subject so there is no bias in choosing order of testing
66
What is a two-way design with two repeated measures?
* 2 repeated measures (= 2 independent variables) - Type of lift (squat/stoop) - Orthosis (yes/no) * Each person exposed to 4 test conditions - 2-way design (2x2 design)
67
What is a Mixed design for multi-factor repeated measure design?
* 2 independent variables - Exercise is independent factor - -2 independent groups (experimental; control) - Time is repeated factor - -3 time periods (pretest; time period 1; time period 2) * 2-way design (2 x 3 design)
68
What do Quasi-experimental designs lack compared to experimental designs?
* Random assignment * Comparison group * Or both
69
What are quasi-experimental designs?
* May involve non-equivalent groups * May be a reasonable alternative to RCT * Conclusions drawn must take into account biases of the sample
70
What occurs in a one-group pretest-posttest design?
* Effect of treatment is determined by change in pre- and posttest scores * Pretest---intervention---posttest * Vulnerable to threats to internal validity because no control group - History - Maturation - Testing
71
What is a one-way repeated measure design over time?
* Effect of treatment over time * Pretest-intervention-posttest 1- posttest 2 * no control group so internal validity threatened
72
What is a Non-equivalent pretest-posttest control group design?
* Similar to pretest-posttest experimental design EXCEPT subjects not assigned to groups randomly e.g. volunteers self-select groups * EXP: Pretest--Intervention--Posttest * CON: pretest--no intervention--posttest
73
What is a non-equivalent posttest only control group design?
* Static group comparison * EXP: intervention --Posttest * CON: no intervention --Posttest
74
What is a single subject design?
* Draw conclusion on treatment effects based on 1 patient’s response * Controlled experimental approach * Independent variable is treatment * Dependent variable is target behavior (outcome) * Also called N of 1 study or Time series designs
75
What is the Structure of a single-subject study?
* Repeated Measurements - Each session; observe trends * At least 2 testing phases: - Baseline (A phase) - Intervention * Target behavior is measured across both phases on multiple occasions * Baseline phase: state of target behavior over time in the absence of treatment (control conditions)
76
In a single subject study, what occurs when treatment starts when talking about change?
* When treatment starts, any change from baseline to intervention phase is attributed to the intervention * Baseline data - comparison for evaluating potential cause and effect relationship between intervention and target behavior * Baseline period = A * Intervention period = B * A-B design
77
How do single subject designs differ from traditional experimental designs?
*Multiple assessments in baseline and intervention phases
78
What are the ethical issues regarding baseline conditions with single subject designs?
*Withholding treatment
79
What are baseline characteristics?
* 2 baseline data characteristics are important for interpreting clinical outcomes - Stability (consistency of response over time): stable or variable - Trend: accelerating or decelerating
80
What is the length of phases?
* Best to have equal phase length * Often 1 week per phase - Daily measurements - Minimum of 3-4 measurements per phase to detect trends * Greater number of data points easier it will be to identify trends * Often measures can be taken more frequently than daily if behavior changes rapidly - More than a single session
81
What are Target Behaviors?
* Choose clinically relevant outcomes measures for a particular patient - Strength - ROM - Gait speed - Balance measures - Pain
82
What are the limitations of A-B Design?
* Experiments can control for threats to internal validity * To do this in the A-B single subject design is more challenging - Other treatments/events (history effects) * What other evidence can we include to strengthen design control ? - to increase confidence that treatment caused the changes in target behavior
83
What is additional Control?
* *Replication of effects * Repeat phases - Withdrawal designs—treatment: no treatment - Withdrawing and reinstating baseline and treatment conditions - Withdraw intervention and show that target behavior occurs only in presence of treatment - -2nd baseline period (A-B-A design) - -Could also include a 2nd intervention phase (A-B-A-B design—see over)
84
What is Data analysis- Visual?
* Visual - Level (last data point of a phase to first data point of next phase) - Trend (direction of change in a phase) - -Accelerating or decelerating - -Slope of a trend (rate of change in the data)
85
What is a Data Analysis- Celebration line used for?
* Used to estimate trends in the data points | * AKA "split middle line" as it divides the data points in a phase into 2 halves
86
What is Generalization?
* Single subject research can provide data for clinical decision making * Not enough to show effect during intervention period on a single patient - Must also be able to show changes in the target behavior will occur in other individuals * Generalization: external validity for the single case * Assume treatment will be effective in others with similar characteristics
87
What is an observational design?
* No manipulation of variables as in experimental designs | * Exploratory or descriptive
88
What is exploratory research?
* Systematic investigation of relationships among variables - e.g. association of leg weakness and falls * Not used to establish cause-and-effect relationships b/w variables
89
How can you conduct exploratory research?
*Retrospectively or Prospectively
90
What is Prospective?
Variables measured in the present and follow subjects in a study **More reliable than retrospective studies
91
What is Retrospective?
* Use of data that have already been collected - medical records, databases * Researcher can't control data collection methods
92
What occurs in Longitudinal Research?
* Follow a cohort over time taking repeated measurements * Can observe growth and change in individuals over time * Often involve large cohorts followed over long periods of time - E.g. Framingham Heart Study (been going 40-50 yrs) * Threats to internal validity relate to - repeated testing - attrition
93
What occurs in Cross-sectional research?
* Gather data as a “snap shot” in time * Very efficient * All subjects tested more or less at same time
94
What is a correlational study?
* Foundation of exploratory studies is process of correlation (degree of association) - Covariation in data (extent to which one variable varies with another variable) * Look at several variables at once to see which are related * can make predictions (predictive correlational study) based on observed relationships between variables - -Cholesterol level: age, diet, gender, genetics, etc - -Regression (stats procedure)
95
What is the purpose of a correlational study?
*Purpose is to describe the nature of existing relationship among variables
96
What is a case-control study?
* Retrospective * not randomized * Purpose of a case-control study is to determine if the frequency of an exposure (e.g. poor nutrition; smoking) is different in cases and controls * Choice of controls is critical - match cases and controls for age, gender, SES, etc.
97
What is the selection bias in case-control studies?
* Selection bias: choose cases and controls regardless of exposure history * Beware of misclassification ie cases and controls
98
What is observation bias in a case control study?
*difference in the way information about disease or exposure is obtained from the groups
99
What is interviewer bias in a case control study?
*Person collecting data elicits, records or interprets info differently from cases and controls
100
What is recall bias in a case control study?
*Subjects remember exposure differently
101
What is a cohort study?
* Follow a group(s) overtime (prospective) * Group 1: Exercisers * Group 2: Sedentary (matched) * Not randomized
102
What is Causality in Observational studies?
* RCT (experimental): cause-and-effect relationships * Case control and cohort studies do not involve experiments or manipulation of variables - Causation (cause and effect i.e. did the exposure cause disease) is established by other methods
103
What is Causality?
* Establish a time sequence: exposure precedes disease * Strength of association: relative risk * Biologic credibility * Consistency with other studies * Dose-response relationship-
104
What is a methodological study?
* Type of exploratory study | * Use correlational methods to examine reliability and validity of measuring instruments
105
What is a historical study?
* Type of exploratory study * A historical study reconstructs the past on the basis of archives and other records to suggest relationships of historical interest to a discipline
106
What populations does descriptive research describe?
* Characteristics * Behaviors * Conditions
107
What does Descriptive research involve?
* May involve prospective or retrospective data collection * Design may be longitudinal or cross-sectional * Surveys and secondary analyses of clinical databases often used as data sources for analysis
108
What are the categories of descriptive research?
* Developmental research * Normative studies * Qualitative research * Descriptive surveys * Case studies / case reports
109
What does developmental research involve?
* Involves description of developmental change and sequencing of behaviors in people over time - motor development in children - lifespan
110
What do longitudinal methods of developmental research involve?
*Longitudinal methods involve collecting data over time—focus on natural history of a disease (eg CMT study)
111
How can you use a cross-sectional study in developmental research?
*Can also use cross-sectional methods and study different age groups at a point in time
112
What is a normative study?
* Purpose is to describe typical or standard values for characteristics of a population * Describe norms as a mean and a range of acceptable values * Norms are used as a basis for prescribing interventions
113
What is qualitative research?
* Describes how individuals perceive their own experiences within a specific social context - What it means to live with a spinal cord injury * Helps us understand the patient’s view of the world - Important in designing interventions * Data collected by interviews and observation - Participant observation (researcher embedded in the group) - Field observation: nonparticipant
114
What are descriptive surveys?
* Often used as a source of data to collect information about a specific group - To describe their characteristics, or risk for disease, or other attributes
115
What occurs in case studies?
* Important for developing a clinical knowledge base * In-depth description of a person’s condition or response to treatment * Case series involves observations in a number of similar cases * Often involve unusual diagnoses that are challenging * May highlight avenues for future research
116
What is the case studies format?
* Comprehensive description of the subjects background, present status, and responses to intervention * Poses questions for further study
117
What does the introduction do in a case studies format?
*Describes background literature to the pts problem
118
what does the pt history do in a case studies format?
*Problems, symptoms, prior treatments, demographic and social info
119
What are the results in a case studies format?
*pts response and any follow-up data
120
What is the discussion in a case studies format?
*Interpretation of outcomes and conclusions
121
What does a case studies format consist of?
* introduciton * pt history * treatment plan * Results * Discussion
122
How do you apply literature to patients?
* Systematic Review * Critically Appraised Topic (CAT) - -Brief Summary of a search and critical appraisal of literature on a clinical question - -Standardized format - -Provides statement of clinical relevance
123
What is a CAT?
* Initiated by a patient encounter usually due to gap in knowledge * Search for and appraises best evidence * Summarizes evidence * Integrates evidence with clinical expertise * Suggest how information can be applied to practice * Usually 1-2 pages
124
How are CATs and systematic reviews similar?
*They both have the goal of applying their information/findings to people
125
What is the format of a CAT?
* Title * Author/date * Clinical scenario (description of case that prompted the question) * Clinical question (PICO format) * Clinical bottom line (summary of how results can be applied) * Search history/strategy * Citations * Summary of the study/ies (design; sample; intervention; outcome measures; data analysis) * Summary of the evidence (results summarized) * Critical comments on the study (internal/external and statistical validity of the study)
126
When do you use CATs?
* Useful at point of care * Can be created out of case conferences * “CAT Banks” established by institutions
127
What are some of the limitations of a CAT?
* Limited shelf life as new evidence becomes available * Not as rigorous as a systematic review - -1-2 references and do not represent full scope of the literature on a topic