calculate the mean and standard deviation of each investment, assume that both returns come from independent samples, are both normally distributed and that the true (but unknown) variances are not the same.
Statistics
Paper, Order, or Assignment Requirements
Question 1
Below are the quarterly returns on investment (in £000s) of two different investment projects which had the same initial outlay. There is a sample of 16 quarters of returns and your manager has asked you to investigate the relative performance of each project. In particular, your manager suspects that ‘Investment B’ outperforms ‘Investment A’ and she would like you to test this hypothesis. Perform an appropriate statistical test that incorporates your manager’s hypothesis.
Hint: in this question you will need to calculate the mean and standard deviation of each investment, assume that both returns come from independent samples, are both normally distributed and that the true (but unknown) variances are not the same.
[25 marks]
Quarter Investment A Investment B
2012Q1 93 85
2012Q2 90 115
2012Q3 82 91
2012Q4 84 118
2013Q1 92 97
2013Q2 95 109
2013Q3 87 103
2013Q4 91 106
2014Q1 91 100
2014Q2 97 100
2014Q3 83 68
2014Q4 96 97
2015Q1 99 92
2015Q2 91 106
2015Q3 90 97
2015Q4 86 87
Question 2
The table below represents the results from 100 different marketing campaigns performed over three different products; the table splits between the products (Product A, B and C), and between the success of the marketing campaign, segregating between those which demonstrate: no increase in sales before and after the campaign; and, an increase in sales compared to before the campaign.
Your manager thinks that the success of the marketing campaigns is different across different products, but she does not know if this result is statistically significant. Test this hypothesis with an appropriate statistical test.
[20 marks]
Product A Product B Product C
No increase in sales 12 7 40
Increase in sales 13 13 15
Question 3
The head office of a large retailer feels that one of its stores is outperforming the overall sales of their UK shops in general. They would like to promote this fact, and further, try to learn and understand more about their success. However, they want to know that this result is a fair interpretation of the data, and ask you to perform a test of statistical significance on this result.
The national monthly sales for the retailer are normally distributed with a mean of £69,000 and a standard deviation of £11,500. For the individual store in question, there are data for 12 months of sales which has a sample mean of £80,000. Perform a statistical test on the claim that the store is outperforming the UK average, assuming that monthly sales are normally distributed.
[15 marks]
Question 4
For one of the questions above, prepare a short report on the results. Do this assuming a wide audience with differing levels of knowledge in the area of statistics and hypothesis testing (therefore, explain the processes involved in simple but formal language). In particular, discuss the following:
The idea behind hypothesis testing and why this is important;
The process performed in order to get the results, the key assumptions in this process, and the appropriateness of these assumptions to the question;
The result, how to interpret the result, and the meaning of the p-value.
Within this, feel free to bring in other knowledge you have from the question which you did not apply in previous questions that you feel would best describe the process and result to a wide audience (for example, calculating other factors from the numbers and/or graphs). This is meant to be a (very brief) report which you would happily present in a business format.
Although there is no formal word limit, 500 words is a good length in order to bring together all arguments required for this question.
[40 marks]