Prove that the set of positive rational numbers is countable by setting up a function that assigns to a rational number p/q with gcd(p, q) = 1 the base 11 number formed by the decimal representation of p followed by the base 11 digit A, which corresponds to the decimal number 10, followed by the decimal representation of q.

Psych 2300: Psychology Research Methods 6/15 & 6/17 Four Validities - Validity: appropriateness of a conclusion or decision Construct Validity Operationalization of a variable Applies to all claims Is this a reasonable way of quantifying what I want to understand Assessing creativity measure x : is x a reasonable way to measure creativity External Validity Generalizability o How was the sample gathered o Can I apply this elsewhere Can these results extend beyond my study Can I apply it to the population I am interested in Who can I apply these results to Representativeness How representative is your sample of the population of interest Specifically interested