A hospital has used control charts continuously since 1978 to monltor the quality of its nursing care. A set of 363 scoring criteria, or standards, are applied at critical points in the patients' stay to determine whether the patients are receiving beneficial nursing care. Auditors regularly visit each hospital unit, sample two patients, and evaluate their care. The auditors review patients' records; interview the patients, the nurse, and the head nurse; and observe the nursing care given (International Journal of Quality and Reliability Management, Vol. 9, 1992).
The data in the table on page 697 were collected over a three-month period for a newly opened unit of the hospital.

a. Construct an R-chart for the nursing care process.

b. Construct an T-chart for the nursing care process.

c. Should the control charts of parts a and b be used to monitor future process output? Explain.

d. The hospital would like all quality scores to exceed 335 (their specification limit). Over the threemonth periods, what proportion of the sampled patients received care that did not conform to the hospital's requirements?