Final answer:
The first step in designing an aptitude test is to identify the skills or abilities that the test should measure.
Step-by-step explanation:
The first step in designing an aptitude test is to identify the skills or abilities that the test should measure. This involves determining what the test taker needs to be able to do in order to succeed in the field or job the test is assessing. For example, if designing an aptitude test for a programming role, the first step might be to identify the specific programming languages and problem-solving skills that are required for success in that role.