Subjective Ratings of Biological Effective Light in Seminar Rooms and How to Handle Small Sample Sizes of Ordinal Data

摘要

Our field study was conducted to examine the influence of biologically effective lighting in students' natural environment. A group of 21 regular master students were exposed to two different lighting scenarios. A developed questionnaire was used to collect subjective ratings according to overall indoor environmental quality. Data produced with questionaires are ordinal data. To analyse this type of data, especially with small sample sizes, an adequate statistical method is needed. This paper uses selected data from the field study to introduce one method based on rank data. Three questions were analysed to compare the subjective ratings of our probands according to the new biologically effective lighting. German seminar rooms or classrooms are built with a high daylight factor. Daylight is a strong confounder for field studies in rooms like that, which can't be controlled in a very good way. We know from other studies that the concentration of carbon dioxid is a second very strong confounder which must be considered. Typical classrooms with 60 - 80 m~2 furthermore limit the sample sizes. As well as know from other lab and controlled field studies that there can be measurable effects in the protection of health. Further testing with classrooms with a less daylight factor or in regions of less daylight might promise a better advantage to students.