Amarketing firm conducts a survey to find out how many people use a product. one hundred people are contacted for the study and fifteen confirm that they use the product. which describes the survey? the marketing firm is going forward in time and observing groups sharing common factors. the marketing firm is applying some treatment to the subjects and then proceeding to observe its effect on the subjects. the marketing firm is observing and measuring specific characteristics of the subjects, but is not attempting to modify the subjects. the marketing firm is going back in time to collect data over some past period