XPD129 Data Handling and Staistics 1 - 3 - 2. To test whether vitamin supplements can help fight cold and flu, a researcher posted a survey on several health websites. The survey asks the participants if they: take vitamin supplements, what type of supplements they take, how many times they suffered from a cold or flu in the previous year and how severe were the symptoms. He found that persons who take vitamin supplements reported fewer instances of cold and flu and with less severe symptoms. (a) Can the researcher claim that taking vitamin supplements will result in fewer instances of cold and flu in the general population Give a reason for your an- swer. [3 mark] You decide to do a placebo-controlled, randomised, double-blind trial on a multi- vitamin supplement to test this claim. (b) Explain what a placebo is and how you would use one in this scenario. [3 mark]- 4. XPD129 Data Handling and Staistics 1 X (c) Explain what double-blind means and how you would implement it in this [3 mark] scenario (d) what is the benefit of randomisation? [2 marks]XPD129 Data Handling and Staistics 1 - 2 - 1. A histogram of variable minutes, which records how many minutes late students were arriving to class, is shown the Figure 1 below. (a) Is minutes a scaled or a categorical variable? [1 mark] (b) What is the range of variable minutes? [1 marks] (c) The markers A, B and C on the histogram are showing the position of the three measures of location: mean, median and mode. State which marker is measur- ing which measure and give reasons for your answer. [4 marks] B Histogram of minutes . B Count - - -.- O 5 minutes Figure 1:XPD129 Data Handling and Staistics 1 - 5 - 3. A typical weight of a gadget produced by a machine is 18.1 gm with standard devi- ation of 0.6 gm. To test if the machine needs calibrating, the weights of 10 gadgets produced were measured, giving the following results: Gadget ID 1 2 3 4 5 6 7 8 9 Weight [gm] |18.2 10 17.3 18.4 18.5 18.2 17.8 16.6 17.9 18.2 17.9 (a) Show the mean weight of the 10 gadgets produced is 17.9 gm. [2 marks] (b) Construct a 95% confidence interval of the mean weight of gadgets. [4 marks] (c) You wish to test if the average calculated is statistically different from the value reported. (i) What null hypothesis will you use? [1 marks] (ii) What is your alternative hypothesis? [1 marks] Continued ...XPD129 Data Handling and Staistics 1 [4 marks] (iii) What test would you use? Calculate the suitable statistic. (IV) State an EXCEL command that could be used to calculate the p-value [2 marks] (d) Should the machine be re-calibrated? Give a reason for your answer. [2 marks]