A sleep researcher conducts an experiment to determine whether sleep loss affects the ability to maintain sustained attention. Fifteen individuals are randomly divided into the following three groups of five subjects each: group 1 which gets the normal amount of sleep (7-8 hours); group 2 which is sleep deprived for 24 hours; group 3 which is sleep deprived for 48 hours. All three groups are tested on the same auditory vigilance task. Subjects are presented with half-second tones spaced at irregular intervals over 1 hour duration. Occasionally, one of the tones is slightly shorter than the rest. The subject's task is to detect the shorter tones. The following data is obtained from the SPSS Output. What can you conclude based on the results? Does a multiple comparison test necessary for this study? Why or why not?