Field tests to compare camouflage patterns rely on collecting data on the preferences of human observers. The director of such tests has been faced with a choice between using pencil-and-paper ballots or using an expensive data collection system based on push buttons wired to personal computers with custom software. In this paper we describe an alternative system that combines the advantages of digital collection with the simplicity of paper ballots. The key ingredients to the system are personal data assistants (PDA's) and database software that runs on a PDA. Specifically, our system makes use of Palm Pilots and the commercial database program thinkDB. Using a stylus, each observer enters his selection of the better camouflage pattern by pushing a radio button on the screen of his Palm Pilot. At the end of the test, the test director uses the Palm HotSync function to transfer the results to a personal computer for analysis.
In field tests to compare the observability of combat vehicles, the test designer must select the optimum number of observation opportunities in order to balance collecting enough data to draw valid conclusions against the high cost of supporting vehicles and personnel at a test site. The test designer, however, generally lacks key parameters for the efficient design of the test. Namely, the designer lacks the detection probabilities of the vehicles at each range. The standard deviation of the difference in detection probability depends upon the detection probability itself. Therefore, the test designer must select the number of observations for each range based upon the conservative assumption that the probabilities are near 50%, the probability for the maximum standard deviation. In this paper, an iterative technique of test design is explored in order to improve the efficiency of observability tests.