Question 5
A researcher is undertaking an early stageinvestigation into the possible effect of a food additive on theweight of rats. The additive is a “designer” chemical aimed atincreasing growth rate. Data from the experiment are contained inthe file STA201 201960 Assignment 2 Rat Diets.xlsx. (a) Show thedata in a structure that allows it to be readily analysed using RCommander. (1 mark) (b) The researcher intends to determine ifthere is evidence that the additive has increased the weight ofrats. State the appropriate null and alternate hypotheses in thisinstance. (c) Show the output when R Commander is used toundertake the relevant Welsch two sample t test, using a 5% levelof significance. (d) Clearly state the conclusion for thetest and justify this by referencing a value or values from the RCommander output. (e) State the statistical assumptionsunderlying Welch’s two sample t test. (f) Say if it wouldhave been appropriate here to use the paired t test and justifyyour decision.
| Additive | Standard |
| 134 | 70 |
| 146 | 118 |
| 104 | 101 |
| 119 | 85 |
| 124 | 107 |
| 161 | 132 |
| 107 | 94 |
| 83 | |
| 113 | |
| 129 | |
| 97 | |
| 123 | |
