Language comprehension appears to decline with advancing age. A study in Applied Psycholinguistics sought to determine which factors contribute significantly to comprehension difficulty. A randomly selected group of paid volunteers was recruited through advertising in local newspapers, and these people agreed to have their hearing tested. The following data represent the pure-tone average (in db HTL) for the subjects who were separated into different age groups (30s, 50s, 60s, and 70s). Test the hypothesis at the .05 level that the population mean hearing level is the same for all age groups. Also, conduct Tukey HSD tests. What would be the interpretation of the results of your analyses.

Thirties 9, 13, 5, 5, 10

Fifties 9, 5, 8, 3, 15

Sixties 19, 8, 14, 26, 25

Seventies 18, 22, 24, 17, 19