3 As part of a study of dental anxiety conducted in Chennai, India, 1148 dental hospital outpatients aged 18–70 years completed the Modifi ed Dental Anxiety Scale (MDAS) (Appukutton et al. 2015).

A high MDAS score indicates a high level of anxiety about dental treatment. A comparison of the MDAS scores for males and females is given below:

Males Females Number of individuals 731 417 Mean MDAS score 10.1 11.1 Standard deviation of MDAS score 3.9 3.9 Difference in mean MDAS score 1.0; P- value < 0.001.

(i) State an appropriate null hypothesis for the MDAS score in the two groups.

(ii) The 95% confidence interval for the difference in means (females minus males) is from 0.5 to 1.5. What does this tell us about adult dental outpatients in India?