Researchers estimate that in a typical month, about 75 billion text messages are sent in the U.S. Text messaging on mobile devices (e.g., cell phones, smart phones) often requires typing in awkward positions that may lead to health issues. A group of Temple University public health professors investigated this phenomenon and published their results in Applied Ergonomics (March 2012). One portion of the study focused on the typing styles of mobile device users. Typing style was categorized as (1) device held with both hands/ both thumbs typing, (2) device held with right hand/ right thumb typing, (3) device held with left hand/ left thumb typing, (4) device held with both hands/ right thumb typing, (5) device held with left hand/right index finger typing, or (6) other. In a sample of 859 college students observed typing on their mobile devices, the professors observed 396, 311, 70, 39, 18, and 25, respectively, in the six categories.
a. Construct a one-way table for the study.
b. Estimate the proportion of mobile device users who hold the device with one hand, using a 95% confidence interval. Interpret the results, practically.
c. Estimate the difference between the proportion of mobile device users who type with both thumbs and the proportion of mobile device users who type with the right thumb, using a 95% confidence interval. Interpret the results, practically.