Final answer:
Attribute sampling is the technique used to infer about a population's rate of occurrence.
Step-by-step explanation:
The sampling technique used to reach a conclusion about a population in terms of a rate (frequency) of occurrence is referred to as Attribute sampling. In the context of the health club example, if the health club decides to ask every tenth customer to complete a short survey about their usage frequency, they are utilizing a systematic sampling method. In this situation, since the customers are not chosen randomly but by a specific order, it is not attribute sampling. However, when discussing sampling techniques such as the one where a sample is studied to infer about a characteristic or rate of occurrence in the larger population, attribute sampling would be the correct term to use.