Biostatistics
Faculty of Veterinary Medicine
Faculty of Veterinary Hygiene and Ecology
MODEL EXAMPLES
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Example No.1 In a stock of dairy cows the glucose level in blood serum was examinated. Measurements of glucose level were performed in a sample of 12 dairycows and following values were measured: 3.1, 3.1, 3.2, 2.8, 2.9, 3.2, 2.7, 2.7, 3.3, 3.2, 3.9, 3.1 mmoll-1. Calculate basic statistical parameters for the sample: mean value, standard deviation (SD) and variance. |
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Example No.2 Body weights were examinated in rabbits in a laboratory breeding. Weighing of 12 rabbits chosen by chance following body weights were measured: 2.7, 3.1, 2.9, 2.7, 3.0, 2.8, 2.9, 2.9, 3.1, 3.3, 2.8, 2.7 kg. What is the average weight of rabbits in the breeding and what is SD and the variance of this body weight? |
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Example No.3
In a horse farm the effect of two veterinary preparations on the Mg level in blood serum of horses has been monitored. In 10 horses, to which the preparation No.1 was applied, the following Mg levels in blood serum have been found (in mmol.l-1): 0.91, 0.79, 0.82, 1.03, 0.82, 0.93, 0.90, 0.87, 0.89, 0.93. In other 10 horses, to which the preparation No.2 was applied, the following Mg levels in blood serum have been found (in mmol.l-1): 0.97, 0.99, 1.24, 1.17, 0.87, 1.20, 0.97, 0.96, 0.99, 0.95. Do preparations differ in its effect on the Mg level in blood serum of horses? |
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Example No.4
In a stock of dairy cows the effect of new veterinary preparation on the AST activity in blood serum of dairy cows has been monitored. In 10 dairy cows (control ones), to which the preparation was not applied, the following AST activities in blood serum have been found (in µmol.l-1 ): 0.337, 0.302, 0.405, 0.400, 0.381, 0.398, 0.377, 0.392, 0.345, 0.409. In 10 dairy cows (test ones), to which the preparation was applied, the following AST activities in blood serum have been found (µmoll-1): 0.341, 0.302, 0.504, 0.452, 0.309, 0.375, 0.479, 0.423, 0.311, 0.333. Does the preparation influence the AST activity in blood serum of dairy cows? |
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Example No. 5 In a horse farm the mean glucose level in blood serum is µ = 3.1 mmoll-1. Energy preparation was applied in feedingstuff to horses and consequently its effect on glucose level in blood serum of horses has been monitored: in the blood samples in 20 randomly chosen horses the following glucose levels in blood serum in v mmoll-1 was found: 3.1, 2.7, 3.3, 3.1, 3.1, 3.2, 3.0, 2.8, 2.9, 2.7, 3.2, 2.7, 2.7, 3.3, 3.2, 3.3, 3.7, 3.9, 3.1, 3.5 Does the preparation influence glucose level in blood serum of horses? |
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Example No. 6 The effect of light regime on egg weight in layers has been monitored. In usual light regime the egg weights in high-density farm has been observed – in randomly chosen 10 layers the following values (g) have been found: 37, 35, 38, 42, 35, 38, 39, 36, 40, 37. Afterwards the light regime in high-density farm was adjusted so that to achieve the higher lay-down (for the same time period). In the same 10 layers the eggs have been weigh again and the following values of egg weights have been found (g): 36, 38, 35, 40, 37, 36, 38, 35, 38, 37. Did the light regime adjustment influence the egg weight in layers? |
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Example No.7
In a stock of dairy cows the effect of new veterinary preparation on the AST activity in blood serum of dairy cows has been monitored. In 10 dairy cows (control ones), to which the preparation was not applied, the following AST activities in blood serum have been found (in µmol.l-1 ): 0.337, 0.302, 0.405, 0.400, 0.381, 0.398, 0.377, 0.392, 0.345, 0.409 In 10 dairy cows (test ones), to which the preparation was applied, the following AST activities in blood serum have been found (in µmol.l-1 ): 0.341, 0.302, 0.504, 0.452, 0.309, 0.375, 0.479, 0.423, 0.311, 0.333 Does the preparation influence the variance of AST activity in blood serum of dairy cows?
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Example No.8
In a horse farm the effect of energy preparation on the glucose level in blood serum of horses was tested. In 10 horses (control), to which the preparation was not apllied, the following glucose levels in blood serum were measured (in mmol.l-1): 3.1, 2.7, 3.3, 3.1, 3.1, 3.2, 3.0, 2.8, 2.9, 2.7 In 10 horses, to which the preparation was applied, the following glucose levels in blood serum were measured (in mmol.l-1): 3.2, 2.7, 2.7, 3.3, 3.2, 3.3, 3.7, 3.9, 3.1, 3.5 Does the preparation influence the variance of glucose level in blood serum of horses?
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Example No. 9 Effects of 3 preparations (A, B, C) for increasing of Mg level in blood serum of dairy cows was tested in an experiment. Four groups of animals were included into the experiment: Control, A, B and C group. Following values og Mg (in mmol.l-1) were measured: Control A B C 1.05 0.91 0.97 1.01 0.69 0.79 0.99 0.96 0.85 0.82 1.24 0.95 0.78 1.03 1.17 0.90 0.82 0.82 0.87 0.99 1.01 0.93 1.2 1.1 0.91 0.9 0.97 0.98 0.88 0.87 0.96 0.9 0.9 0.89 0.99 0.95 0.85 0.93 0.95 0.86 Calculate basic statistical parameters in every group and evaluate differences between effects of individual preparations A, B, C with respect to Control sample. Represent differences found in a graphical form. |
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Example No.10
Find out whether a correlation between acidobasic exudation (ABE) and pH of urine exists in dairy cows. In an experiment following values were measured: ABE (mmoll-1) pH (-log H+) 20 7.0 10 7.2 50 8.0 90 7.6 135 7.9 150 8.3 173 8.0 195 8.1 205 8.6 229 8.1 263 8.0 Calculate correlation coefficient and figure a chart of linear regression (with calculated trendline equation) of the relation between these sample data. |
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Example No. 11
Find out whether a correlation between glucose level in blood serum and keto-substances in urine exists in dairy cows. In an experiment following values were measured:
glucose (mmoll-1) keto-substances (units) 2.5 0 2.6 0 2.8 2 2.9 1 3.0 2 3.1 3 3.2 2 3.5 4 3.9 2 4.2 4 4.5 3 Calculate correlation coefficient and figure a chart of linear regression (with calculated trendline equation) of the relation between these sample data. |
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Example No. 12
Find out whether a correlation between body weight and eggs weight exists in layers. In a sample of 10 layers following body weights (in kg) were measured: 2.2, 1.8, 2.1, 1.7, 2.4, 2.0, 2.0, 1.9, 2.3, 1.9 In these layers following egg weights (in g) were measured (average value from 10 eggs): 41, 36, 40, 36, 42, 39, 40, 37, 41, 38. Calculate basic statistical parameters (AVG, SD) in each sample, calculate correlation coefficient and figure a chart of linear regression (with calculated trendline equation) of the relation between these sample data. |
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