8.5 Quick review questions

Formwork is used in construction using reinforced concrete. It is complicated and labour intensive. An observational study (Mine et al. 2015) examined the relationship between the floor area of the building (in m² per storey) and the number of hours of labour needed for the construction (in person-minutes per storey).

The researchers also recorded, among other things:

• the average age of the workers (in years);
• the average years of experience of the workers (in years); and
• the storey height (in meters)

for each of \(n=15\) multi-storey buildings in the study. Some data was obtained from

… interviews [..] conducted with the relevant person-in-charge of scheduling for each project.

— Mine et al. (2015), p. 2

To record the number of person-hours of labour:

Two observers made the site rounds observation of 2 to 40 workers. Observations were carried out continuously from the start to the end of work, excluding lunch time.

— Mine et al. (2015), p. 2

1. The explanatory variable is
   Floor area Hours of labour Average age of workers Average years of experience of workers Storey height
2. The response variable is
   Floor area Hours of labour Average age of workers Average years of experience of workers Storey height
3. What is the best description for the variable ‘Average age of the workers?’
   A confounding variable, since it is likely to be related to the explanatory variable only A confounding variable, since it is likely to be related to the response variable only An extraneous variable, because it is likely to be related to the response variable only A lurking variable, since we don’t know how it might be related to the response and explanatory variables
4. What is the most likely way in which confounding would be managed in this study?
   Restricting, the study to multi-storey buildings Blocking, by only studying unit blocks Analysis, by using other recorded variables in the analysis Random allocation of workers to the building projects
5. True or false: The carry-over effect is likely to be a big problem in this study.
   TRUE FALSE
6. True or false: The Hawthorne effect is likely to be a big problem in this study.
   TRUE FALSE
7. True or false: The placebo effect is likely to be a big problem in this study.
   TRUE FALSE
8. True or false: The observer effect is likely to be a big problem in this study.
   TRUE FALSE

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