Note: You are expected to use Minitab for your analyses with the output incorporated into your report.
The objective of this observational study is to investigate an aspect of traffic behaviour. From a sample of cars (or other vehicles), you must collect three measurements for each car/vehicle. The measurements need to include one (1) continuous numerical variable and two (2) categorical variables; one of the categorical variables needs to have two levels, and the other needs to have 3 or more levels.
You do not need equal sample sizes BUT you do need at least 10 measurements per level in each categorical variable.
Choose ONE of the three following research questions to investigate:
1. Is the distance of a parked car from the kerb different for different types of vehicle and/or whether the car was made before or after 2005?
2. Is the length of time indicating affected by the type of vehicle (eg. Car, van, SUV, motorbike, etc) driven and/or the gender of the driver?
3. Is the distance beyond or before the double lines where a car stops at an intersection affected by the age of the driver (young, middle age, older) and/or whether or not there are any passengers?
Prepare a report of no more than 5 pages, using the following headings and addressing the points stated under each heading.
Part A: Introduction
• State the research question you investigated.
• Describe the variables you used and how you measured them including the units used for your numeric variable.
• Describe the population of interest.
Part B: Data collection:
• Describe how you collected your data, what you did and why you made the decisions you did. Enough information should be given so that someone else could repeat your sampling method. Include:
o Details on how you selected your sample
o Comments on any practical difficulties you encountered and
o Changes you would make to your data collection method if you were going to repeat this task.
o Details of where and when your data were collected.
Part C: Data analysis:
Use Minitab and incorporate the output into your report
1. Simple descriptive analysis
• For your 2 level categorical variable produce:
i. Side-by-side dotplots and boxplots of your numerical variable.
ii. Numerical summaries of your numerical variable for each level of the categorical variable. Include the sample size, mean, standard deviation and the five number summary.
• For your 3+ level categorical variable produce:
i. Side-by-side dotplots and boxplots of your numerical variable.
ii. Numerical summaries of your numerical variable for each level of the categorical variable. Include the sample size, mean, standard deviation and the five number summary.
• Describe the important features of your data, as shown by your graphs and numerical summaries.
2. Confidence intervals
• For your 2 level categorical variable, produce:
i. A 95% confidence interval for your numeric variable for each level of the categorical variable.
ii. Interpret each confidence interval in the context of your research question
• For your 3+ level categorical variable produce:
i. A 95% confidence interval for your numeric variable for each level of the categorical variable.
ii. Interpret each confidence interval in the context of your research question
Part D: Discussion and Conclusion
This section should include, but is not limited to, the following:
• Discuss what your analysis tells you about your research question.
• What can you conclude about your population of interest?
• Discuss whether you can generalise what you have learnt about your research question beyond the population of interest.
• Critique the way you selected your sample. You should comment on:
o Independence
o Sampling error
o Non-sampling error and
o How well your sample represents your population of interest.