ABSTRACT
Experimental designs differ from other research designs in the degree of control exerted by the researcher over the conditions under which data are collected. When observational or survey designs are employed, the researcher measures the variables of interest but does not attempt to manipulate or control the variables. However, as mentioned in Chapter 2, in experimental (causal) designs, researchers measure, manipulate, and control different variables. For example, a retailer trying to isolate the influence of price changes on the sales volume of a product, must identify the nonprice variables such as location of the product in the store, time period of the day/week, promotion, etc., and control these variables because they also influence sales volume. Simply altering price and measuring sales is not an adequate design because of the impact of nonprice variables on sales.
