Two types of aerosol, X and Y were compared in asthmatic people. 85 people were included in a cross-over trial. Each individual used each aerosol for a period of month, with the order of administration at random. For 19 people their symptoms were better controlled while on aerosol X and for 36 whilst they were on aerosol Y. 26 people did well on both X and Y and 9 failed to complete the trial.

i) Draw 2x2 table

ii) Is there any evidence of a difference in the effect between aerosol X and Y?

iii) give brief summary of results.