Practicals 8: F-test and ANOVA
Data for these practicals are available in an Excel spreadsheet.
1. Temperature of water in one pot was measured by different thermometers manufactured by two
companies: Termom and Celsimet. Each of them provided 10 thermometers for the testing, The aim
of the testing was to detect potential systematic bias (whether the thermometers of one company
show in average different values from those made by the other) and whether there is a difference in
accuracy. The data were as following:
Termom: 18, 19, 18, 17, 16, 19, 18, 17, 19, 18 Celsimet: 17, 15, 21, 20, 19, 22, 15, 16 ,18, 17
Test both differences in mean values and in the accuracy between the two manufacturers. Would
you buy a thermometer produced by any of these companies? Voluntary task: go to a homeware
shop, check thermometers there and let the class know if the temperature pattern is similar to
Termom, Celsimet or different from both.
2. In a fertilizer application experiment, plants growing in pots (one plant/one pot) were fertilized
by different kinds of fertilizer. Dry-weight of above ground biomass was determined for each pot at
the end of the experiment. The resulting masses we following:
Type of fertilizer Biomass DW in g
Water (control) 87,95,74,85,89,97
Mineral NPK diluted in water 140,180,155,164,157,149
Mineral solid slowly decomposing NPK 150,190,165,185,171,182
Ammonium nitrate 123,145,136,134,141, 131
Organic manure 145,161,175,149,141, 169
Does application of different types of fertilizer affect plant biomass? If yes, how?
A. Distribution of four bird species on gradient of altitude was studied in Moravia by recording
altitudes of their nests. The resulting data were as following:
Species Nest altitude (m a.s.l.)
Sea eagle
160, 180, 224, 175, 305, 280
Blackbird
780, 540, 180, 380, 685, 430
Raven
1200, 830, 450, 1050, 870, 930
Red crossbill
780, 830, 680, 1005, 970,950
Does the mean of the altitudinal range significatly differ between the species?
B. Number of insect herbivore species were recorded on three species of trees in a forest (9
randomly chosen individuals per species). Following numbers of herbivore species were recorded:
Beech: 3,5,4,3,7,8,4,6,5
Spruce: 8,3,6,7,3,4,6,5,5
Lime: 10,7,15,12,9,8, 12, 11, 7
Do the tree species differ in the species richness of herbivore communities? If yes, how?
C. 20 experimental rats were given 4 types of nutrition. Effect of these types of nutrition on rat
intelligence was measured by the time the rats needed to find a way from a labyrinth.
Nutrition Time in seconds
Control nutrition 56,75,65,85,74
Fat enriched 102,108,95,84,115
Sugar enriched 85,92,75,69,79
Control nutrition + beer 45, 56,53,61,57
Does nutrition have an effect on rat intelligence? How do individual nutrition types affect rat
intelligence?
D. Wheat (Triticum aestivum) was cultivated in pots with three different substrates: sandy, clay and
peaty. Chlorophyll concentration [μmol per cm2
of leaf area] was then analyzed in leaves of the
experimental wheat plants. The results are summarized below.
sandy soil: 50, 45, 61, 54, 48, 42
clay: 53, 61, 59, 49, 58, 69
peaty soil: 31, 40, 41, 28, 35, 37
Does the soil type have a significant effect on chlorophyll concentration?
E. Speed of cars was measured by traffic police on the Nové Sady Street in Brno. The drivers
exceeding the speed limit 50 km h-1
were punished by a fine. In addition to the speed, car colour
was recorded. The resulting speed data (in km h-1
) were following
red cars: 50, 52, 47, 43, 40, 49, 49, 75, 48, 50, 48, 49
blue cars: 65,50, 47, 75, 45, 38, 67, 57, 54
black cars: 45, 76, 58, 53, 54, 50, 48, 49
yellow cars: 38, 49, 54, 49
Is the driving speed associated with car colour? Should the police focus more on drivers driving
cars of a particular colour?