A different coffee seller offered to sell coffee to Jenae's company for half the cost of their current brand. Jenae knew her co-workers were really partial to the coffee they drank now, so she decided to conduct a study to see if they noticed the difference in flavor. Her co-workers were convinced they would. To avoid any bias, Jenae had a friend provide each person with a sample and said that some had the new coffee and some did not. Not even Jenae knew who had which brand of coffee. Jenae's strategy is an example of a(n