Write an appropriate null hypothesis.

A study by Heyman et al. (2008) examined a sample of 245 elderly individuals living in long-term care facilities. Each had a grade II–IV pressure ulcer. The pressure ulcers were examined at enrollment and then again at 3 and 9 weeks. All of the patients received standard care plus an additional nutritional supplement. The goal of the study was to examine the effects of the nutritional supplement plus routine care on the healing of pressure ulcers in long-term care patients. (See Figure 10-2.)

(mm) Pressure ulcer area 2000 1500 1000 500 0 Baseline * I Visit 2 *A H Visit 3 Mean data + SE *p