Experiment Project

(Adapted from "What Is the Use of Experiments Conducted By Statistics Students?", by Margaret Mackisack, Queensland University of Technology, Journal of Statistics Education v.2, n.1 (1994))

For this project you will design an experiment, collect data, and analyze the data using the tools of this course. You will select the subject of your experiment. You will be working in groups of 3 or 4.

Deadlines

Design of the Experiment:

Progress Report:

Analysis of Data:

Final Report:

Each group will turn in just one copy of each part.

Choosing a Subject

The attached list contains outlines of experiments that have been carried out by students for similar projects at other universities, to give you an idea of the sort of thing you might choose. You may repeat one of these, or select your own. Remember, you have to carry out the experiment and collect (at least preliminary) results in four weeks, so don't choose something which is going to take a long time to accumulate data. An experiment which makes use of some activity which you would perform anyway, or some skill that you have, is usually the most satisfactory. Your experimental subjects must be inanimate - the only people involved in the experiment should be your group. So you may not survey or otherwise involve other students/friends/family, etc. This is because experiments involving humans or live animals (even class projects) require approval by the university's Institutional Review Board, which is a lengthy and tedious process.

The Design

You will be studying the effect of one factor, with at least three levels, on a response variable. Your design must:

· Specify the response variable. You may be measuring either a quantity (e.g. time it takes to boil water) or a proportion (e.g. percentage of baskets made); in any case, your variables should be quantitative, rather than categorical.

· Describe the factor you have chosen to study, and the levels. Explain your hypotheses - how do you expect the response variable to differ at the different levels? Or do you have no expectation? These initial hypotheses will affect how you use statistical tests!

· Identify your pool of experimental units. Preferably, you should use similar experimental units so that no blocking is needed.

· Carefully describe your method for assigning the treatments to the experimental units. If you use the random number table (or the random number generator on your calculator), describe how. Be sure that your experiment explicitly uses randomization in some way.

· Identify at least three other specific factors that might influence your response variable and describe how your experimental design attempts to eliminate such biases.

· It is strongly recommended that you discuss your design with other groups, or with the professor, because explaining to someone else what you plan to do is an excellent way to become aware of aspects that you have overlooked.

Carrying Out the Experiment

Your group must actually carry out the experiment yourselves, and yourselves cause the factors influencing the outcomes to vary, do appropriate randomization of the allocation of treatments to experimental units, etc. Collecting together data which has been obtained by somebody else, even if it appears to fit into the framework of your experimental design, is not acceptable. You must obtain at least 20 observations at each level of your factor.

You will turn in a Progress Report consisting of your new experimental design, updated to reflect comments on the previous plan and encounters with reality, and a preliminary set of data. While the data collection need not be complete, it must be sufficient for you to have identified and corrected any major problems with your design. These corrections (if any) should be pointed out and discussed.

Analyzing and Reporting on the Results

You will choose the appropriate tools to analyze your results. These may involve histograms and summary statistics, regression, inference about means or proportions, and combinations of these tools. Your analysis should include appropriate background about your design, plots and tables of results, and significant facts that emerge from the analysis.

Written Reports

This should be organized and presented in a lucid and orderly manner with appropriate diagrams and graphs included. It should be typed, and follow the Writing Guidelines for Projects and Reports as appropriate. The report will include the final experimental design, all the data collected, and the results of your analysis. It should say or show all the things you decided, did or discovered along the way, including the simple ones (and particularly the things which, with hindsight, seem obvious!). You do NOT have to have statistically significant results, although the chances are that they will be if you design your experiment well. Considerable weight will be given to evidence that you have actually been thinking about what you are doing, and why, and what it all means, and how you could improve upon it.

List of Student Experiments

The experiments are listed in the form Response/Factors. In most cases, several factors are listed. For those marked (?) it was difficult to control extraneous variation, and significant results were not obtained.

Response	Factors
distance golf ball hit with full force	tee height, ball age, club type
squash ball rebound distance	ball type, ball age, ball temperature
distance soccer ball kicked	kick style, angle to goal, angle of ball
number of pins down	bowling ball weight, spin, position for throw
water evaporation	surface area, sun or shade, volume at start
car acceleration	time to gear change, road surface, car type (?)
number of baskets thrown	ball size, distance from net
letter delivery time	post code, mailbox or post office, town (?)
speed running	distance, terrain, time of day
distance paper airplane flew	design, paper weight, angle
long jump distance	runup distance, shoes on or off, L or R foot
time to swim 25m	shirt on or off, flippers, goggles
number of meat ants on sandwich	butter, filling, bread type
time to skip 100	L, R or both feet, forward or back, rope weight
time to deliver pizza	crust thickness, garlic bread, Coke
time to boil water	amount of water, lid on or off, size of pan
virus scan time	RAM cache, program size, operating system (?)
reaction time to grab rod	width of rod, L or R hand, eyes open/shut
number of pull-ups achieved	time of day, warm-up, taking inosine
height rise of scones	amounts of butter, flour, milk
time to read short passage of text	font, size, upper/lower case
number of tennis serves in	direction of gaze, stance
time to be served at supermarket	items, location, time of day
height off ground jumped	type of shoe, run-up, starting foot
time to run 5km	chocolate/banana, coffee/beer, time before run (?)
distance cricket ball hit	weight of bat, wearing gloves (?)
life of rosebuds	stem length, aspirin in water, refrigeration
number of corns popped/100	pot diameter, oil or margarine
casting distance	rod length, line weight, sinker weight
drops of water held by a coin/area	type of coin, heads or tails, age