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 “£” stands for British Pounds Sterling, “cig” stands for cigarettes, and “N/A” refers to a missing component of the data.
library(openintro)## Please visit openintro.org for free statistics materials##
## Attaching package: 'openintro'## The following objects are masked from 'package:datasets':
##
## cars, treesdata(smoking)
summary(smoking)## gender age maritalStatus highestQualification
## Female:965 Min. :16.00 Divorced :161 No Qualification :586
## Male :726 1st Qu.:34.00 Married :812 GCSE/O Level :308
## Median :48.00 Separated: 68 Degree :262
## Mean :49.84 Single :427 Other/Sub Degree :127
## 3rd Qu.:65.50 Widowed :223 Higher/Sub Degree:125
## Max. :97.00 A Levels :105
## (Other) :178
## nationality ethnicity grossIncome
## English :833 Asian : 41 5,200 to 10,400 :396
## British :538 Black : 34 10,400 to 15,600:268
## Scottish:142 Chinese: 27 2,600 to 5,200 :257
## Other : 71 Mixed : 14 15,600 to 20,800:188
## Welsh : 66 Refused: 13 20,800 to 28,600:155
## Irish : 23 Unknown: 2 Under 2,600 :133
## (Other) : 18 White :1560 (Other) :294
## region smoke amtWeekends amtWeekdays
## London :182 No :1270 Min. : 0.00 Min. : 0.00
## Midlands & East Anglia:443 Yes: 421 1st Qu.:10.00 1st Qu.: 7.00
## Scotland :148 Median :15.00 Median :12.00
## South East :252 Mean :16.41 Mean :13.75
## South West :157 3rd Qu.:20.00 3rd Qu.:20.00
## The North :426 Max. :60.00 Max. :55.00
## Wales : 83 NA's :1270 NA's :1270
## type
## :1270
## Both/Mainly Hand-Rolled: 10
## Both/Mainly Packets : 42
## Hand-Rolled : 72
## Packets : 297
##
## ## creating a subset out of the original matix
SmokingHabitsUK = subset(smoking,
select = c(gender,age,maritalStatus,grossIncome,smoke,amtWeekends,amtWeekdays))
names(SmokingHabitsUK)[1]="sex"
names(SmokingHabitsUK)[3]="marital"
str(SmokingHabitsUK)## 'data.frame': 1691 obs. of 7 variables:
## $ sex : Factor w/ 2 levels "Female","Male": 2 1 2 1 1 1 2 2 2 1 ...
## $ age : int 38 42 40 40 39 37 53 44 40 41 ...
## $ marital : Factor w/ 5 levels "Divorced","Married",..: 1 4 2 2 2 2 2 4 4 2 ...
## $ grossIncome: Factor w/ 10 levels "10,400 to 15,600",..: 3 9 5 1 3 2 7 1 3 6 ...
## $ smoke : Factor w/ 2 levels "No","Yes": 1 2 1 1 1 1 2 1 2 2 ...
## $ amtWeekends: int NA 12 NA NA NA NA 6 NA 8 15 ...
## $ amtWeekdays: int NA 12 NA NA NA NA 6 NA 8 12 ...head(SmokingHabitsUK)Each row of the data matrix represents its case or Observational unit. In this case it represent information on an individual UK resident smoking habit.
nrow(smoking)## [1] 1691There were 1691 participants included in the survey
In this study, there are both numerical and categorical variables.
Numerical
-> Continous : age
-> discrete: amtWeekends, amtWeekdays
Categorical
-> Nominal: sex, marital, smoke
-> ordinal : grossIncome
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 15. 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.
The population of interest of this study are 160 children between the ages of 5 and 15.
The sample in this study were the children who attended a summer camp in italy in the two days that the experiment was conducted.
The results of this study cannot be generalized to the population as this sample of the study does not represent all the children in that age group. Also in the experiment they rewarded students who only reported white and this can affect on children’s dicition making.Children were not informed about the nature of the experiment.Experiment was given to them as part of their camp activity. These reasons can also contribute to a biased experiment. Yes it is possible to establish a casual relationship as this is an experiment and the results were different when half of the children were told not to cheat expricitly.
ref: Alessandro Bucciol and Marco Piovesan. “Luck or cheating? A field experiment on honesty with children”. In:Journal of Economic Psychology
Reading the paper. (1.28, p. 31) Below are excerpts from two articles published in the NY Times:
“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.”
Data analyzed were from a survey rather than from an experiment that involves control groups. It is difficult to conclude that smoking cause dementia later in life just based on those outcomes from the survey. Not just Dementia, participants ended up with Alzheimer’s disease as well. And also we have no information on what are the other factors that were adjusted to come to an conclution too.
“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.”
Above study does not prove that sleep disorders lead to bullying in school children. It is the other way around. Data collected from the survey shows that the children with behavioral issues and those who were identified as bullies like to have symptoms of sleep disorders.
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.
Based on the information, this is an experiment type study that involves control group with treatment(exercise)
Treatment Group -> randomly picked half of 18-30, 31-40 and 41-55 year olds from the sample population. (exercise twise a week) Control Group -> rest of 18-30, 31-40 and 41-55 year olds from the sample population. (No exercise)
This study users age groups such as 18-30, 31-40 and 41-55. This is a way of blocking using age as its blocking variable.
This study does not use blinding. All the individuals are instructed to do or not to do exercises and have done mental evaluations begining and end of the study. It does not mention in the study too.
This is an experiment study that can be used to establish a casual relationship between exercise and mental health. If the sample size is big enough, the conclution can be generalized to the population at large.
I would have some reservations. As the control group is informed not to exercise at all, that may lead to decrease in physical health with their mental health. Eventhough the reasearch target is to mesure the mental health, experiment might do some serious damage to individuals overall health.