Independent Variable
-manipulated
-intervention
Dependent Variable
-measured
-change in strength
Confounding Variable
-variable that could influence outcome of the study
Quantitative Research
-uses numbers
-IV manipulated
-reduce confounding variable
-t-test, ANOVA, mean med mode
-control is important
Qualitative Research
-understand a problem from the perfpective of the affected population
-interviews
-no control or manipulation of IV
Strengths:
-descriptions
-human side of issues
Limitations:
-time and cost
-cannot measure validity and reliability
-cannot be generalized
Single-Subject
-one or few participants measured several times
-usually unique pop or intervention
Nominal Scale
-qualitative
-identified only by name
-show differences in individuals
ex: gender, disease, zip code
Ordinal Scale
-qualitative
-ordered categories
-direction of differences between individuals
-no true number value (“subjective” numbers)
ex: no help, some help, independent, MMT
Interval/Ratio Scale
-quantitative
-ordered series of equal size
-direction and magnitude
Interval: zero is arbitrary
Ratio: real zero
ex: feet, temp, ROM, speed
Descriptive Studies
-Retrospective
-Normative
-qualitative
-describes data
Exploratory Studies
-correlational: relationships
-predictive: reliability and validity
-case control (quasi experimental)
Experimental Studies
-RCT only true
-cause and effect
Quasi-Experimental
-no manipulated IV
-pre exisiting variable
-cohort studies
You’re comparing two groups to see if something makes a difference.
But, you didn’t randomly choose who eats carrots and who doesn’t. You just used two classes that already existed.
ex: pre/post, dx A vs dx B
Alpha Level
-predetermed before study
-pre set significance level
-0.05 usually, 5% chance data relationships are not significant
Smaller: high risk - consequences of Type I error are high (false positive)
Larger: important even if theres a chance at not being effective
P-Value
-determined by outcome of study
-actualy probability that results occured by chance
- <0.05 to be significant (reject null hypothesis)
Validity
Internal Validity of Study
-did the IV cause the change in DV
-RCT is the best design to maximize
“where my methods sound?”
Internal Validity: History
-something happend between pre and post to change result
You are interested in studying the effects of an aquatic exercise program at varying intensities in
those individuals that are s/p CVA. All of the participants are at least 1 year post-stroke. You
randomly select 60 individuals for placement into three groups. One group will receive aquatic
therapy 3 x per week (180 minutes). One group will receive aquatic therapy 1 x per week (60
minutes) and one group will not receive any aquatic therapy. All individuals must provide their
own transportation. All groups will be asked to exercise at least 180 minutes per
week….therefore, if not in the pool, they will be performing a home exercise program. As part of
the pre-intervention testing, all participants completed a battery of physical performance tests
including the 6 minute walk. You recruit all of your participants from a local stroke survivor
support group by sharing a flyer with the group leader. It is October in Houston and the weather
has just cooled off so the support group will start their outdoor walking program for interested
individuals
Internal Validity: Maturation
-did participants change over time
ex: children aging, disease progression
During a class early in PT school, the students were given an exam on the best ways to approach the care of an individual with RA. Then the students were given 5 modules on the care of patients with RA during the first semester. Due to midterms and other classwork, the follow-up exam (determining if the educational intervention made a difference in the students’ learning) was given at the end of the 2nd semester.
Internal Validity: Attrition/Mortality
-who dropped out and why
Dr. Mitchell is conducting a study at the Star of Hope Homeless shelter in Houston. She has
trained 6 shelter volunteers to provide fun active games (as well as education on wellness) for the
children and their mothers on a daily basis to determine if there is an impact on their quality of
life both in the short and long-term while homeless. The volunteers start the program with 75
mother/child pairs. Over the course of the first week, 4 pairings are placed in temporary housing.
And over the next 6 weeks, all find temporary or permanent housing. 82% of the pairings return
for the follow-up testing
Internal Validity: Repeated Testing
-did the repetiitons change the outcome
ex: doing the same thing for weeks will ensure better performance
A PhD student was interested in the ability of individuals post-stroke to learn a new motor task with their lower extremity in a seated position. The participants were given a home program and
tested every week for six weeks to determine if the home program was improving their ability to perform the task.
Internal Validity: Instrumentation
-was the instrument changed
-calibrated
A PhD student was interested on whether or not an in-school exercise intervention could impact children with high BMIs in inner-city Houston. The outcome measure was weight, BMI and
percentage body fat and was tested at the beginning of the school year and again at the end of the school year. The intervention was to provide short duration, high intensity exercise bouts in
their school classroom by their teacher. The children were tested at seven different HISD
elementary schools using the PE teachers’ scales and the measurements were all done by the same researcher
Internal Validity: Regression to the Mean
-groups with extreme scores tend to regress towards mean
ex: really bad pt will get better and really good might stay or get worse closer to the mean
You are a researcher at TIRR and are conducting a study in collaboration with TWU professor. You
are interested in the impact of whole-body vibration on bone density in those individuals with post-polio syndrome. You recruit 30 participants with post-polio and randomly divide them into two groups. One group will receive the whole body vibration and the other will receive a sham treatment. The participants bone density was measured prior to the 4 week intervention and immediately following the intervention. The treatment group had a mean bone density pre- intervention of **T=-2.8 **and the sham group had a mean bone density pre-intervention of T=-1.8.
Following the intervention, the treatment group had a mean of T=-2.0 and the sham group had a mean of T=1.8. There was no difference between the groups after the intervention
Internal Validity: Experiementer Bias
-biased
Dr. Gleeson is the former head of the APTA education section and one of the main individuals responsible for CI training in the state of Texas. Dr. Gleeson is interested in studying the professional behaviors of CIs as viewed by the CIs themselves as well as by their students. All of the selected CIs have participated in Dr. Gleeson’s CI training courses. The students consent to participate at the start of the rotation and their views regarding their CIs are assessed half-way
through the rotation. The CIs are asked to consent half-way through the rotation and are assessed via a qualitative semi-structured interview at the end of the rotation. Dr. Gleeson will be conducting all of the interviews