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Research Design: Case study and Single Subject Design

Case Study (defined by Bromely 1990)
Systematic inquiry into an event which aims to describe and explain the phenomenon of interest. We are interested in the overall effect, clinicians are interested at an individual level.
What does a case study give special attention to? (Zonabend 1992)
Completeness in observation, reconstruction, and analysis of the cases under study
What was the american crowbar case and who was involved?
Phineaus Gage got a metal rod through his frontal lobe and his personality changed.
What are three advantages of a case study?
1) provides an in-depth analysis of how the variables of interest affect each other
2) potentially more informative
3) Less expensive
what are 2 disadvantages of case studies?
1) external validity (difficult to extend to the general population)
2) Ample opportunity exists for the biases of the researcher to colour the case description
What were the findings of Prapavessis (1992) state anxiety and sport performance study? Why?
Equivocal (uncertain). Possibly due to operation definitions of anxiety and performance of individual difference (intra subject vs inter group variation)
What are three suggestions from Mace (1990) that Prap took to heart for his state anxiety study?
1) Athletes must demonstrate symptoms of anxiety that are detrimental to performance in order for interventions to be useful
3) The effectiveness of the intervention is enhanced if a considerable amount of time is devoted to the specific needs of the athlete
3) training and testing conditions should simulate the conditions under which the athlete must perform
Describe the athlete involved in Prap's state anxiety study.
- 20 yo male state level small bore riffle shooter
- rated controlling cognitive and somatic state anxiety his worst mental skills
What kind of subject selection is inappropriate for case control studies?
Random selection
Describe the dependent measures (for state anxiety) used for praps state anxiety study
1) Self- report (CSAI-2): if reduced performance increases
2) Electromyographic response (EMG): muscle tension
3) Electrocardiographic response (ECG): HR
4) Biochemical response (urine catecholamine and adrenaline concentrations): indicate anxiety
5) Behavior response (accelerometry): at the end of the gun, measures movements (shaking)
6) performance: distance of bullet hole from centre (avg of 20 rounds)
Describe Prap's Treatment Procedure for state anxiety
- preliminary session to minimize stress sensitivity
- baseline (on site during a real comp); control to ensure that the athlete was comfortable wearing the measurement equipment
- intervention (self regulated program- 12 sessions over a 6 week period; breathing and stretching, progressive muscle relaxation, thought stoppage, ECG biofeedback- summarized into audiotapes)
- post intervention: onsite during another real competition (note what happens as a result of intervention)
Describe the results of Prap's state anxiety study in terms of a) self report cognitive anxiety b) self report somatic anxiety c) self-report state confidence d) Urinary noradranaline e) urinary adrenaline f) accelerometer (gun vibration) g) Heart Rate h) Forearm (EMG) i) performance error
a/b) unnecessary physiological responses; decrease in somatic/ cognitive anxiety
c) systematic increase in confidence after each round (greater post treatment)
d/e) lower scores indicating less physcial stress
f) linear decrease in accelerometry
g) HR was not clear cut; some rounds decreased and some increased
h) forearm is unclear
i) error decreased linearly
Explain the effect of expectancy and how it can be dealt with
Expectancy is when results change based on what you expect them to be. Dealt with by blinding and placebos
What are the a) environmental and b) personal threats to internal validity of the state anxiety study?
a) temperature, wind, importance
b) diet, sleep, training
What were the limitations of Praps state anxiety study?
expectancy effect and generalization of findings
what are the advantages of single subject design?
1) many repetitions of measurement; provides potentially valuable information on individual variation in performance
2) Only a few subjects needed to evaluate an intervention (one)
3) Easily identifies within and between subject changes
4) everyone receives the intervention
not hampered by statistical assumptions (required for group design research)
5) emphasizes social validation
Characteristics of single subject designs
1) on going assessment of the dependent variable
2) each subject receives both control and treatment conditions (they are their own control)
Describe inter-observer reliability (IOR) of the dependent measure.
Divide the smaller total of the dependent variable by one observer by the larger total recorded by the second observer; multiply by 100. IOR scores >80% are considered acceptable (Kazdin 1994)
Name 3 types of single subject design
1) replication-reversal (ABAB)
2) Multiple baseline
3) Alternating Treatment
Describe internal validity
Ability to turn on or turn off behavior each time the treatment is introduced or withdrawn
Describe External validity
Results can be generalized over a number of subjects
What are the advantages of altering treatment design?
1) allows for the comparison of treatments within an individual over time
2) detects delayed treatment effects
3) all conditions can be introduces concurrently, avoids lengthy baseline and treatment conditions
What are the disadvantages of altering treatment design?
1) Interaction may occur because of similarities between the conditions
2) conduct a few additional sessions with the most effective treatment at the end of the study. if the performance continues at the same level as when treatment was alternated with other conditions, then it is unlikely that an interaction occurred
What characteristics give confidence in data?
- baseline data are stable
- the greater the number of times that an effect is replicated both within and across subject
- the sooner the effect occurs following the introduction of the treatment
- the larger the size of the effect in comparison to baseline
- results are consistent with existing theory
Why is using visual inspection advantageous for decision making?
If it's large enough to see it's likely to be significant. The eye doesnt pick up subtle change.
How close are visual techniques to statistical techniques in terms of detecting change?
86% agreement between the two
Name the 3 statistical tests used in single subject design
1) split middle
2) 2 SD method
3) Trend (time series analysis)
Describe Trend (time series) analysis
- trend line analysis is computed at baseline and treatment and the lines are compared for differences
Describe the split middle method
get notes!
Calculation for SD
= square root of (x-m)squared/ (N-1)
Name five misunderstandings of single subject design
1) similar to case studies; lack internal validity (CHECK)
2) lacks external validity
3)visual inspection of data is subjective and not scholarly
4) can't be used to compare alternative treatments
5)cant be used to detect small effects
When do Reboussin and Morgan (1996) find ssd useful?
in early stages for hypothesis generation