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Fitting a Regression Lines - A Formal Statement of a Null Hypothesis - Information Management Assessment Answer
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Internal Code: 6CIFE
Information Management Assessment Answer
TASK: QUESTION 1) FITTING A REGRESSION LINES In the folder for this assignment, there is a data file ”var.csv” that includes 180 observations on nitrogen fertiliser application and yield. The first 90 observations are for a traditional variety while the next 90 are for a modern or improved variety. Information on the variety type is also included in the data file. Answer the following questions using the data set. (a) Plot crop yield against fertiliser rates for the two varieties on the same plot but distinguishing the two varieties by colour. Add a legend identifying the varieties to the plot. (b) Summarise the data on yield and nitrogen fertiliser rates for the two crops. Present your data summary in a table form including the minimum, maximum, median, mean, standard deviation and coefficient of variation for the four variables (i.e. yield and nitrogen by variety). (c) Fit a linear regression model for the traditional variety and describe the results. Your model should have yield as the ’y’ variable and nitrogen as the ’x’ variable. As part of your results description, write out the estimated equation for the relationship between yield (y) and nitrogen (n) together with the R-squared value. Interpret the results. (d) Do the same for the modern variety. (e) Create a data plot like that you did for exercise (a) above and add the two regression lines to that plot. (f) Suppose you have been asked to predict the expected crop yield for a nitrogen rate of 75 kg/ha using your estimated regression results for the modern variety. What would your prediction be? And what would the 99% confidence interval for that prediction be? Add the predicted value and the 99% confidence interval to the plot with the regression lines. QUESTION 2) FITTING A REGRESSION LINE In the same folder, there is a data file which has data on apple production in Australia covering three decades in the second half of the twentieth century (apl.csv). The data are extracted from the FAOSTAT database and include information on production areas in hectares (”area”), output in tonnes (”production”), yield in hectograms per hectare (”yield.hgha”), and time tends variable (”time”). You have been asked to investigate if yield levels are related to time and the nature of any such relationship. Conduct a structured investigation of this theory using the data available. Your report should include: (a) A description of the data set using a summary table (including means, medians, standard deviations, etc.) (b) An appropriate graphical representation of the data, together with plots of the regression lines you estimated. Include a legend to describe the regression lines. Do not clutter your plot by adding too many regression lines; two regression lines would be sufficient – one for the linear model and another for a nonlinear one (e.g. quadratic or other). See (e) below. (c) A formal statement of a null hypothesis. (d) A discussion of whether the linear functional form is appropriate for describing the relationship between yield and time. (e) Results from one alternative equation (e.g. nonlinear in variables). Estimate, present and interpret the results from your second regression. This should include a summary of why you think your second model is better suited to answering the research question than the first.This Management Assignment has been solved by our Management experts at onlineassignmentbank. Our Assignment Writing Experts are efficient to provide a fresh solution to this question. We are serving more than 10000+ Students in Australia, UK & US by helping them to score HD in their academics. Our Experts are well trained to follow all marking rubrics & referencing style.