## A.1 Answer: TW 1 tutorial

Ask the question. Design the study. Collect the data. Classify and summarize the data. Analyse the data. Report the results.

1. Either is OK; they are just different. Note the different way a study can be addressed. But importantly: neither RQ is actually helping answer the issue of the cafe owner! For example, I may be able to tell the difference between diet and regular cola... but I may like them both equally (i.e., the test rating is the same).
2. The cafe owner would not allocate drinkers to drink either diet or regular soft drinks, but just find those who were drinking either and ask them to rate the taste. I guess a non-directional study (cross-sectional study) would be best.
3. The cafe owner would need to allocate drinkers to either diet or regular. Ideally, the drinkers would not know which they had consumed (really, that's next week's work). Ideally, the drinks would be allocated at random to receive diet or regular (next week too). Ideally a true experiment.
4. Experimental would be better; fewer things out of the researchers control. Besides, people buy what they like...

You can use the Glossary in the textbook.

P: People at an American college. O: The average time taken to walk $$50$$ m. C: Between the way subjects were using their phone. I: None: an observational study.

Explanatory variable: The way that the phone is being used. Response variable: The time taken to walk $$50$$ m.

Unit of observation: Individual subjects. Unit of analysis: Individual subjects.

1. Many populations are possible. The "best" population: the easiest, or cheapest to get? All of the options are possibilities.

2. "Relaxing": Many options possible for quantifying this (heart rate? breathing rate? survey? change in heart rate before and after drinking the tea?).

3. Again, many options are possible, Some options for comparing to Earl Grey tea: coffee; hot water; black tea; nothing at all; anything else but Early Grey; etc.

4. "Between before and after drinking Earl Grey tea" is not a betwee-individuals comparison because everyone in the population (sample) is treated the same way: there are not two groups in the population being compared.

5. An example RQ might be:

"Among UniSC students (P), is the average heart rate $$30$$ mins after drinking (O) different between those who drink a cup of Earl Grey tea and those who drinking a cup of hot coffee (C) when the drink is provided to them (I)?"

I'm not saying this is the best; it is just an example.

6. Get volunteers; place into one of the groups (Earl Grey and coffee); give the beverage; measure heart rate after $$30$$ mins. Note that many design issues are not covered until the next lecture.

7. An example RQ might be:

"Among UniSC students (P), is the average heart rate 30 minutes after drinking (O) is different between those who drink a cup of Earl Grey tea and those who drinking a cup of hot coffee (C)?" I'm not saying this is the best; it is just an example.

8. Based on the above RQ: Find UniSC students who drink Earl Grey tea, and others who drink coffee, and measure their heart rate $$30$$ mins after they drink.

It would have a lot of confounding effects to account for.

9. For my RQ above: The volume of tea or coffee; brand of tea or coffee; how made; when beverage taken; how long steeped for; how heart rate is measured; student (full-time only?); etc. You don't need to define these, but if you have time you can have a go at one or two definitions.

10. Many options, but for the RQ above: type of beverage; heart rate after $$30$$ mins (or better, the change in heart rate).

1. The unit of analysis is the floorboard: because one board is compared to another; because the hardness is a feature of each board, not each test; because the two measurements on each board are not independent of each other (from the same board).
2. There are $$5$$ units of analysis.
3. There are $$10$$ units of observation.
4. Now, only one unit of analysis.
5. Within boards, the variation is small, apart from Board 1. Between boards it is larger.

Answers implied by H5P. Observational. Quasi-experimental (the classes are determined by the students, but the lecturer decides which class gets which treatment).

The answers, in alphabetical order, are: ask; collect; data; design; evidence; qualitative; quantitative.

1. Should be in terms of averages or means. So perhaps "Among water tanks used in south-east Queensland, are the average lead levels in tank water in concrete tanks higher than in poly tanks?"
2. Everyone dies!
So a time-frame is probably meant (i.e., twelve months after amputation). And compared to what? Perhaps something like: "Are lower-limb amputees more likely to die $$12$$ months after amputation compared to upper-limb amputees?" or something.
3. No defined population (frozen beans? fresh butter beans? tinned kidney beans? jelly beans? coffee beans? can sizes?); "amount" of salt should be, for example, the "average" amount (or concentration) of salt, and per $$100$$ g or similar. "Is the mean amount of salt in tinned butter beans the same for Woolworth's Select brand as for Edgells brand?" Anyway: You can look at the label (unless, of course, you wish to query those values).
4. Silly: elephants are huge, and joeys are tiny. No-one needs to test this. Also,the RQ talks about "weight" rather than "mean weight" too.
5. Needs to be more specific! Perhaps: "Is the mean reaction time different for males and females?" or similar.

Terms that may need defining (there may be others):

1. Conceptual: Domestic; "SE Queensland"; poly tanks; concrete tanks.
Operational: How the concentration will be measured.
2. Conceptual: Lower-limb amputee.
3. Conceptual: "Amount" of salt; Homebrand; beans (coffee beans? jelly beans; bean-bag beans; kidney beans; baked beans; etc.)
Operational: how is salt "amount" being measured?
4. Conceptual: adult; juvenile; what type of kangaroos and elephants?
Operational: How to measure weight (especially of elephants!)
5. Conceptual: Reaction time; gender. Operational: How reaction time will be measured. How gender will be determined.

1. The population is: a. $$2$$-year-old infants in Cincinnati.
2. The outcome: c. The average of the indexes of the $$2$$-year neurobehavioural development.
3. The comparison: b. Between low-to-moderate pre/post exposure to lead and no pre/post exposure.
4. The intervention: d. There is no intervention.
5. The unit of observation: b. The children.
6. The unit of analysis: b. The children.

Units of analysis: a. The individuals ingots. Sample size: d. $$80$$.