Question

Wheat.CSV

2. (17 marks) An agricultural scientist wishes to understand the effect of weed biomass (g/m2) on wheat yield loss (the percentage of the expected wheat mass that was not reaped). For 40 wheat fields (all the same size) in southern Saskatchewan, he measured the weed biomass and the wheat yield loss. The data are available in the file wheat.csv. Is this an observational study or an experiment? Explain. (2 marks) b. What is the likely population of interest? Include justification for your answer. (2 marks) What is the sample? (1 mark) d. How would you classify the sample: a simple random sample, voluntary response sample, or convenience sample? Explain. (2 marks) Do you expect the sample f. Create a scatterplot of wheat yield loss vs. weed biomass. Comment on the overall pattern of the plot (direction, form, strength), g. Compute the sample correlation between wheat yield loss vs. weed biomass. Provide an interpretation of your value. (3 marks) а. с. to be biased? Explain. (2 marks) е. as well as any outliers. (5 marks) "weed.biomass", "percentage.loss" 12,59 32,91 16,73 35,92 38,87 2,16 21,75 36,96 22,77 18,89 38,83 18,77 27,99 23,74 4,39 36,87 10,54 2, 21 13,79 38,32 36,95 28,78 26,85 40,92 26,98 28,89 22,93 24,96 12,75 6,48 39,95 36,95 28,97 32,78 1,0 19,72 30,89 9,62 13,66 9,52

Answer 1

a) This is an observational study. He has no control over the variables.

b) Wheat fields are population of interest. Data can be collected from any wheat field. Our main focus is on the effect of weed biomass on wheat yield.

c) 40 wheat fields of same size from South Saskachewan is the sample.

d) This is a convenience sampling, as he selected a particular geographical area of his own convenience, irrespective of the fact that he wants to conclude about the effect in general.

e) With respect to the geographical area, the sample is biased.

g) r= 0.7233, hence, they are significantly correlated