SNAILS Data: Species Exposure Rel.Hum Temp Deaths N 1 A 1 60.0 10 0 20 2 A 1 60.0 15 0 20 3 A 1 60.0 20 0 20 4 A 1 65.8 10 0 20 5 A 1 65.8 15 0 20 6 A 1 65.8 20 0 20 7 A 1 70.5 10 0 20 8 A 1 70.5 15 0 20 9 A 1 70.5 20 0 20 10 A 1 75.8 10 0 20 11 A 1 75.8 15 0 20 12 A 1 75.8 20 0 20 13 A 2 60.0 10 0 20 14 A 2 60.0 15 1 20 15 A 2 60.0 20 1 20 16 A 2 65.8 10 0 20 17 A 2 65.8 15 1 20 18 A 2 65.8 20 0 20 19 A 2 70.5 10 0 20 20 A 2 70.5 15 0 20 21 A 2 70.5 20 0 20 22 A 2 75.8 10 0 20 23 A 2 75.8 15 0 20 24 A 2 75.8 20 0 20 25 A 3 60.0 10 1 20 26 A 3 60.0 15 4 20 27 A 3 60.0 20 5 20 28 A 3 65.8 10 0 20 29 A 3 65.8 15 2 20 30 A 3 65.8 20 4 20 31 A 3 70.5 10 0 20 32 A 3 70.5 15 2 20 33 A 3 70.5 20 3 20 34 A 3 75.8 10 0 20 35 A 3 75.8 15 1 20 36 A 3 75.8 20 2 20 37 A 4 60.0 10 7 20 38 A 4 60.0 15 7 20 39 A 4 60.0 20 7 20 40 A 4 65.8 10 4 20 41 A 4 65.8 15 4 20 42 A 4 65.8 20 7 20 43 A 4 70.5 10 3 20 44 A 4 70.5 15 3 20 45 A 4 70.5 20 5 20 46 A 4 75.8 10 2 20 47 A 4 75.8 15 3 20 48 A 4 75.8 20 3 20 49 B 1 60.0 10 0 20 50 B 1 60.0 15 0 20 51 B 1 60.0 20 0 20 52 B 1 65.8 10 0 20 53 B 1 65.8 15 0 20 54 B 1 65.8 20 0 20 55 B 1 70.5 10 0 20 56 B 1 70.5 15 0 20 57 B 1 70.5 20 0 20 58 B 1 75.8 10 0 20 59 B 1 75.8 15 0 20 60 B 1 75.8 20 0 20 61 B 2 60.0 10 0 20 62 B 2 60.0 15 3 20 63 B 2 60.0 20 2 20 64 B 2 65.8 10 0 20 65 B 2 65.8 15 2 20 66 B 2 65.8 20 1 20 67 B 2 70.5 10 0 20 68 B 2 70.5 15 0 20 69 B 2 70.5 20 1 20 70 B 2 75.8 10 1 20 71 B 2 75.8 15 0 20 72 B 2 75.8 20 1 20 73 B 3 60.0 10 7 20 74 B 3 60.0 15 11 20 75 B 3 60.0 20 11 20 76 B 3 65.8 10 4 20 77 B 3 65.8 15 5 20 78 B 3 65.8 20 9 20 79 B 3 70.5 10 2 20 80 B 3 70.5 15 4 20 81 B 3 70.5 20 6 20 82 B 3 75.8 10 2 20 83 B 3 75.8 15 3 20 84 B 3 75.8 20 5 20 85 B 4 60.0 10 12 20 86 B 4 60.0 15 14 20 87 B 4 60.0 20 16 20 88 B 4 65.8 10 10 20 89 B 4 65.8 15 12 20 90 B 4 65.8 20 12 20 91 B 4 70.5 10 5 20 92 B 4 70.5 15 7 20 93 B 4 70.5 20 9 20 94 B 4 75.8 10 4 20 95 B 4 75.8 15 5 20 96 B 4 75.8 20 7 20 Description: Groups of 20 snails were held for periods of 1, 2, 3 or 4 weeks in carefully controlled conditions of temperature and relative humidity. There were two species of snail, A and B, and the experiment was designed as a 4 by 3 by 4 by 2 completely randomized design. At the end of the exposure time the snails were tested to see if they had survived; the process itself is fatal for the animals. The data are unusual in that in most cases fatalities during the experiment were fairly small. Format: - Species snail species A (1) or B (2). - Exposure exposure in weeks. - Rel.Hum relative humidity (4 levels). - Temp temperature, in degrees Celsius (3 levels). - Deaths number of deaths. - N number of snails exposed. Task: Model the probability of survival in terms of the stimulus variables, and in particular to test for differences between species.