Many workers in an electronics assembly plant have been reporting tingling sensations in the hand, which, in many cases, has been diagnosed as CTS. Initial observations indicate the use of high levels of pinch forces to insert wires into connectors. An ergonomist has suggested measuring the grip force ratio (force used divided by minimum force required) on a tracking task as a screening tool for CTS (the median nerve innervates the index finger) in addition to diagnostic testing of CTS by a physician. Seven workers with strong symptoms of CTS are evaluated on the tracking task. Seven relatively similar symptom-free workers are also evaluated on the tracking task. The jobs of both sets of workers are studied for evidence of high-pinch forces. The following data was obtained:

1. What type of epidemiological study was used in the plant?
2. What are the implications (i.e., limitations) for this type of study?
3. Are the groups well matched? (Hint: Perform t-test on various characteristics.)
4. What is the prevalence of CTS in workers exposed to high-pinch forces?
5. What is the prevalence of CTS in workers not exposed to high-pinch forces?
6. What is the OR for incurring CTS due to exposure of high-pinch forces?
7. Is this a statistically significant result? Use a = 0.05.
8. What does a chi-square analysis indicate?
9. Is the grip force ratio a good screening tools for CTS? Consider a ratio over 6 to be
   excessive.
10. Does it appear that any of the individual characteristics (age, gender, wrist circumference, max pinch force) may predispose one to CTS? (Hint: Perform OR s on a binary breakdown for each characteristic. For example, consider 45 years as a dividing line between young and old workers.)
11. What are your overall conclusions regarding this plant and study.
     

CTS Gender Yes M Yes F Yes F Yes F F F M M F F F F F M Yes Yes Yes No No No No No No No Age 35 35 57 45 56 29 43 31 40 62 45 47 33 45 Wrist Circumference (mm) 184 168 156 187 193 145 189 168 159 161 153 151 166 174 Grip Force Ratio 7.4 7.7 10.0 6.0 4.0 5.6 7.2 5.0 4.6 5.0 4.6 5.4 3.8 3.2 Exposure to High Forces Yes Yes Yes Yes No No Yes No No Yes No Yes No No