Smoking habits of UK residents. (1.10, p. 20) A survey was conducted to study the smoking habits of UK residents. Below is a data matrix displaying a portion of the data collected in this survey. Note that “\(\pounds\)” stands for British Pounds Sterling, “cig” stands for cigarettes, and “N/A” refers to a missing component of the data.

  1. What does each row of the data matrix represent?
Each row represent a single observation.
  1. How many participants were included in the survey?
1691 observations so 1691 participents.
  1. Indicate whether each variable in the study is numerical or categorical. If numerical, identify as continuous or discrete. If categorical, indicate if the variable is ordinal.
sex: Categorical, Nominal
age: Numerical, Discrete
marital: Categorical, Nominal
grossIncome: Categorical, Ordinal
Smoke: Categorical, Nominal
amtWeekends: Numerical, Discrete
amtWeedays: Numerical, Discrete

Cheaters, scope of inference. (1.14, p. 29) Exercise 1.5 introduces a study where researchers studying the relationship between honesty, age, and self-control conducted an experiment on 160 children between the ages of 5 and 151. The researchers asked each child to toss a fair coin in private and to record the outcome (white or black) on a paper sheet, and said they would only reward children who report white. Half the students were explicitly told not to cheat and the others were not given any explicit instructions. Differences were observed in the cheating rates in the instruction and no instruction groups, as well as some differences across children’s characteristics within each group.

  1. Identify the population of interest and the sample in this study.
Population of Interest is children between age 5 and 15.
Sample in the study is 160 children between those ages.
  1. Comment on whether or not the results of the study can be generalized to the population, and if the findings of the study can be used to establish causal relationships.
The study cannot be genralized as to the genral population becasey the sample is not IID 
as they werent taken randomly. Since the study was part of a randomized self controlled 
experiment, it can be used to establish a causal relationship.

Reading the paper. (1.28, p. 31) Below are excerpts from two articles published in the NY Times:

  1. An article titled Risks: Smokers Found More Prone to Dementia states the following:

“Researchers analyzed data from 23,123 health plan members who participated in a voluntary exam and health behavior survey from 1978 to 1985, when they were 50-60 years old. 23 years later, about 25% of the group had dementia, including 1,136 with Alzheimer’s disease and 416 with vascular dementia. After adjusting for other factors, the researchers concluded that pack-a- day smokers were 37% more likely than nonsmokers to develop dementia, and the risks went up with increased smoking; 44% for one to two packs a day; and twice the risk for more than two packs.”

Based on this study, can we conclude that smoking causes dementia later in life? Explain your reasoning.

We cannot use the term causes as this is an observational study and not a randomized 
controlled experiment. Here we can only say that therir  is stronf relationship or 
coreelation between the two variables. Furthermore the study is is not random as it
made up of volunteers and their must be soem type of bias.
  1. Another article titled The School Bully Is Sleepy states the following:

“The University of Michigan study, collected survey data from parents on each child’s sleep habits and asked both parents and teachers to assess behavioral concerns. About a third of the students studied were identified by parents or teachers as having problems with disruptive behavior or bullying. The researchers found that children who had behavioral issues and those who were identified as bullies were twice as likely to have shown symptoms of sleep disorders.”

A friend of yours who read the article says, “The study shows that sleep disorders lead to bullying in school children.” Is this statement justified? If not, how best can you describe the conclusion that can be drawn from this study?

Once again there is only a relationship or correlation between these two variables
and not causation since no random controlled experiment was conducted. Thus the 
staement is not justifiable.

Exercise and mental health. (1.34, p. 35) A researcher is interested in the effects of exercise on mental health and he proposes the following study: Use stratified random sampling to ensure rep- resentative proportions of 18-30, 31-40 and 41-55 year olds from the population. Next, randomly assign half the subjects from each age group to exercise twice a week, and instruct the rest not to exercise. Conduct a mental health exam at the beginning and at the end of the study, and compare the results.

  1. What type of study is this?
Randomized Block Experiment
  1. What are the treatment and control groups in this study?
Treatment group is the half which were instructed to excercise
Control group are the other half which were instructednot to excersise.
  1. Does this study make use of blocking? If so, what is the blocking variable?
Yes, the study used blocking. The blocking variable are ages (18-30,31-40,41-55)
  1. Does this study make use of blinding?
No blinding used in this study since all the stakeholders know that they are 
part of the study and know if they are part of the control or treatment group.
  1. Comment on whether or not the results of the study can be used to establish a causal rela- tionship between exercise and mental health, and indicate whether or not the conclusions can be generalized to the population at large.
Yes, since this is a controlled experiment, we can establish a coausal 
relationship between excercise and mental health.  However we have to be 
carefull not top generalize this to the population as there might be bias 
in the study if the random sample already do not excersise then there will
be a small change in their mental health behavior, or the opposite where
a sample of the populatiuon already excercise and they might also show 
a sign of smaller changes in their mental health.
  1. Suppose you are given the task of determining if this proposed study should get funding. Would you have any reservations about the study proposal?
Yes, there is still some type pof bias and blinding need to be used to 
remove that bias.

  1. Alessandro Bucciol and Marco Piovesan. “Luck or cheating? A field experiment on honesty with children”. In: Journal of Economic Psychology 32.1 (2011), pp. 73-78. Available at https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1307694↩︎