1. Research Design
1.1. Randomized control trial of two groups
1.1.1. Tai Chi group
1.1.2. Control group
2. Population, sample and type of sampling
2.1. 14 female nurses aged 49 years old and up
2.1.1. picked on a first come basis
2.1.1.1. 7 inthe control group
2.1.1.2. 7 in theTai chi intervention group
2.2. one year of experience
2.3. work in direct patient care
2.4. able to attend 15 weeks of class
2.5. 40 years of age or older
3. Threats to Validity
3.1. Internal
3.1.1. History
3.1.1.1. unable to attend classes
3.1.1.2. Stressful live events
3.1.1.3. Injuries
3.1.2. Maturation
3.1.2.1. biological or psychological processes that occur over time
3.1.2.1.1. Normal aging process
3.1.2.1.2. Normal mental sharpness decline
3.1.3. Testing
3.1.3.1. Took the same tests more than once, possibly influencing the participant's responses
3.1.4. Instrumentation
3.1.4.1. Did the same person administer both tests to decrease the chance that the techniques could be different
3.1.5. Mortality
3.1.5.1. Three participants dropped out, one out of the Tai Chi group and two out of the control group, no one died
3.1.6. Selection bias
3.1.6.1. The mean level of the work limitations was higher in the Tai Chi group than the control group which offered a greater chance for change from the baseline
3.2. External
3.2.1. Selection effect
3.2.1.1. Small study was the biggest limitation
3.2.1.2. single geographic area used
3.2.1.3. No men participated in the study and no underrepresented populations
3.2.2. Reactive effect
3.2.2.1. How did the subjects respond to being studied and tested
3.2.3. Measurement effect
3.2.3.1. The baseline test could have acted like an intervention and influenced the participants to make changes in their lifestyle
3.2.3.1.1. Diet and exercise changes in both groups due to initial testing
3.2.4. unable to dissect instructor effects due to individual style