3 In a study of the attitudes in the American dental profession towards the Medicaid scheme for affordable care targeted at those with a low income, 651 dentists based in Iowa were asked whether they currently accepted new Medicaid patients into their practice

(McKernan et al. 2015). A comparison of those living in a metropolitan county of Iowa with those living in a non- metropolitan county gave the following results:

Metropolitan Non-metropolitan Number of dentists 371 280 Number accepting new Medicaid patients 194 172 Percentage accepting new Medicaid patients 52.3% 61.4%

Difference in percentage accepting new Medicaid patients (nonmetropolitan

– metropolitan) = 9.1% (two signifi cant fi gures), 95%

confi dence interval for difference 1.4% to 16.8%, P = 0.02.

(i) State an appropriate null hypothesis for the acceptance of new Medicaid patients by metropolitan and non- metropolitan dentists in Iowa.

(ii) What does the 95% confi dence interval indicate about the willingness of metropolitan and non- metropolitan dentists to accept new Medicaid patients?