FIG 3.

Subjective feedback. (a) Round-robin A/B testing of net preferences among prototypes 1 to 3 (large bold numbers) and the control (C). Each arrow points from the less preferred to the more preferred swab. Arrow weight indicates strength of relative preference. Preferences were unanimous except where noted with numbers separated by a slash: the first number is the number of responses for the direction indicated by the arrowhead, while the second number is the number of responses that had the opposite preference. The weight of the arrow is proportional to the difference (e.g., 7 − 3 = a net preference of 4). Unless otherwise noted, each arrow represents 12 to 15 separate responses. (b) Numbers of positive and negative comments received from study staff who administered the swabs, tabulated by category. In each plot, negative feedback is to the left of the zero, while positive feedback is to the right. The presence of bars on both the positive and negative sides of zero reflects different opinions among study staff. n, total number of comments received about each prototype from study staff.