1. Because local dental anesthetic administration is often accompanied by patient anxiety and other adverse sequalae, a study of effectiveness of high frequency neural modulation (similar to that used in physical therapy to control chronic pain) to prevent pain during a variety of procedures, including restorations and tooth extractions. People were given either the electrical stimulation or simply had the inactive device attached as though it were being used (a placebo control). Neither the dentist nor the patient knew whether or not the neural modulator was turned on. Do the following data suggest that the high-frequency modulation is an effective analgesic? Use both xˆ2 and zstatistics.