Alliance for Lighting InformationAlliance for Lighting InformationAs for the subjective analysis portion of the work, the survey shown in appendix B utilizes two-valued logic. S. I. Hayakawa wrote in Language in Thought and Action:
'The term "two-valued orientation" was originated by Alfred Korzybski, whose main concern was with the orientations that determine health or disorder in people's semantic reactions. Although he described the two-valued orientation as characteristic of a primitive or emotionally disturbed outlook, he was not attacking two-valued logic. Ordinary logic, such as we use in arithmetic, is strictly two-valued. Within the framework of ordinary arithmetic, two plus two are four. This is the "right" answer, and all other answers are "wrong".'
Hayakawa further wrote: "On the whole, therefore, except in mathematics and other areas where clear-cut linguistic agreements either exist or can be brought into existence, the assiduous study and practice of two-valued logic is not recommended.
"It is interesting to note that even in mathematics, stress is laid today on the fact that two-valued logic is only one of the many possible systems of logic. The logic of probability, on the basis of which insurance companies quote premiums, bookmakers quote odds and physicists predict the behavior of neutrons, may be regarded as an infinite-valued logic."
Two-valued logic is not appropriate for scientific evaluations, especially in subjective analysis. John Flynn, one of the founders of research into the psychological aspects of lighting, used multi-valued scaling (seven steps) in his semantic differential scaling models. Since two-valued logic only allows for yes or no answers, the data, in statistical terms is almost meaningless since the data will not fall into a 'normal distribution curve'. It takes a minimum of three points to establish a curve. Without a normal distribution, statistical methods such as 'mean', 'standard deviation', and 'confidence intervals' are not valid.
In addition, there was some important information left out of the survey that should have been included in a subjective study. First, the respondents' age information was not recorded. The human visual system degrades with age, so the age of a respondent is important in subjective analysis of visual surroundings. For example, older eyes are more susceptible to glare but also require more contrast than younger eyes. Second, there was important information about the visual scene that was not included in the research; specifically there is no information about the paving material in the visual scene. Since asphalt has a reflectance of about 7.5 percent and concrete has a reflectance ranging from 18 to 34 percent, a concrete parking lot will appear 3.4 to 4.5 times as bright as an asphalt parking lot lighted to the same illuminance. This reflected light can significantly alter an observer's adapted luminance level and thus alter the perception of safety and the sensation of glare. The data does not include any information about the boundary conditions of the 'functional use area' being evaluated, such as the presence of a brightly lighted building directly adjacent to the area or another lighted parking lot or an open field. What were the sizes and how bright were the surfaces within the visual scene? Was the respondent alone or with someone else? How many other people were in the surroundings? Third, there is no time stamp as to when the survey was administered. Time of day can have an important implication for the safety one feels: one may be comfortable alone in a parking lot at 6:00pm on a December evening, but not at 11:30pm. Fourth, there is no information regarding the condition of the respondents' visual systems. Did they have perfect 20/20 vision or did they wear corrective lenses? Fifth, there is no information available about where the surveys were administered other than what 'functional use area' the respondents were viewing. There is no indication whether the survey was administered in a parking lot directly under a luminaire, between luminaires or at the building entry. Finally, there is no indication as to the respondents' familiarity with the site - do they live nearby, have they been to the site previously, do they work at the facility. Familiarity is a key component of an individual's perception of safety and security.
This report is trying to associate all the psychological implications of safety and security with one component (lighting) of a vast array of emotional and perceptual input and stimulation that influence the perception of safety and security.
Furthermore, from reviewing the data, it appears that no more than two surveys were administered at any given site. In many instances only one survey was administered at a site. This is tantamount to showing a different piece of artwork to 400 different people and then trying to draw some conclusion as to how art makes all people feel or whether people like museums. This makes the data statistically insignificant, and only suitable for consideration as opinion. Better, more informative data could have been gathered by administering many surveys at a few sites.
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