The commands below load these R packages and will appear at the top of all your R Markdown homework files.

Problem 1: Explain the difference between a population and a sample.

Answer: A population is a collection of all people of subjects that you are wishing to make an inference about. While a sample is a subset of the events, subjects, or objects that you use to make an inference about the whole population.

Problem 2: Classify the following variables as categorical (qualitative) or quantitative.

  1. Favorite musical group,categorical
  2. Address, categorical
  3. Height Quantitative
  4. Number of students at a university quantitative
  5. Number of cats owned quantitative
  6. Miles per hour at which a car is traveling Quantitative
  7. Phone number categorical
  8. Amount of money spent on Netflix this year Quantitative

Problem 3: Identify the population and sample of the following research objective:

A college notices that an increasing number of full-time students are working while attending the school. The administration randomly selects 128 students and asks how many hours per week each of them works.

Answer: The population if full time college students that attend the college in question.

Problem 4: Determine whether the following study depicts an observational study or an experiment.

Rats with cancer are divided into two groups. One group receives 5 miligrams(mg) of a medication that is thought to fight cancer, and the other receives 10 mg. After 2 years, the spread of of the cancer is measured.

Answer: experiment

Problem 5: Are young couples who marry or cohabitate more likely to gain weight than those who stay single? Researchers followed 8000 men and women for 7 years. At the estart of the study, none of the participants were married or living with a romantic partner. The researchers found that women who married or cohabitated during the study gained 9 pounds more than single women, and married or cohabitating men gained, on average, 6 pounds more than single men.

  1. Why is this an observational study?
  2. What is the response variable in the study? Explanatory variable?
  3. Identify some potential lurking variables in this study
  4. Can we conclude that getting married or cohabiting causes one to gain weight? Explain.

Answer:1. it is an observational study because the researcher has no control over the variables in this test. 2. The response variable is the amount of weight gained by each individual 3.Some lurking variables would be peoples time commitments, people who dont spend time working out have more time to seak a relationship. 4.No, because there are so many other factors that could be affecting this, while it may strongly correlate it may not be because of the cohabitation, or marriage itself but because of other factors.

Problem 6: Define simple random sampling. Answer: simple random sampling is a type of unbiased sampling that allows every individual in the population to have an equal chance of being selected for the study as the next individual.

Problem 7: Using the AllCountries data set, list the variable names and the first few cases using the head() command in R. Try also using the command names() to get just the variable names.

Answer: ountry Code LandArea Population Energy Rural Military HealthCountry" “Code” “LandArea” “Population”
[5] “Energy” “Rural” “Military” “Health”
[9] “HIV” “Internet” “Developed” “BirthRate”
[13] “ElderlyPop” “LifeExpectancy” “CO2” “GDP”
[17] “Cell” “Electricity” “kwhPerCap”

head(AllCountries)
##          Country Code LandArea Population Energy Rural Military Health HIV
## 1    Afghanistan  AFG   652230     29.021     NA  76.0      4.4    3.7  NA
## 2        Albania  ALB    27400      3.143   2088  53.3       NA    8.2  NA
## 3        Algeria  ALG  2381740     34.373  37069  34.8     13.0   10.6 0.1
## 4 American Samoa  ASA      200      0.066     NA   7.7       NA     NA  NA
## 5        Andorra  AND      470      0.084     NA  11.1       NA   21.3  NA
## 6         Angola  ANG  1246700     18.021  10972  43.3       NA    6.8 2.0
##   Internet Developed BirthRate ElderlyPop LifeExpectancy        CO2       GDP
## 1      1.7        NA      46.5        2.2           43.9 0.02503483  501.4709
## 2     23.9         1      14.6        9.3           76.6 1.31285501 3678.2317
## 3     10.2         1      20.8        4.6           72.4 3.23296040 4494.8867
## 4       NA        NA        NA         NA             NA         NA        NA
## 5     70.5        NA      10.4         NA             NA 6.52783463        NA
## 6      3.1         1      42.9        2.5           47.0 1.35108829 4422.5428
##        Cell Electricity  kwhPerCap
## 1  37.80711          NA       <NA>
## 2 141.92896   1747.0980 Under 2500
## 3  92.42126    970.9825 Under 2500
## 4        NA          NA       <NA>
## 5  77.17642          NA       <NA>
## 6  46.68924    202.1545 Under 2500

Problem 8: Run Knit HTML to convert your R markdown to a web page document.

Problem 9: In the resulting window, proofread your markdown document. When you’re satisfied that everything is correct click on “Open in Browser”, select “print”" from your browser, and then “Save as PDF”. Upload the resulting PDF to the assignment area in Moodle.