Definitions
When we take a census, we attempt to collect data from whom?
Who is every individual in the population.
You want to take a simple random sample (SRS) of 50 of the 816 students who live in a dormitory on campus. You label the students 001 to 816 in alphabetical order. In the table of random digits, you read the entries 95592 94007 69769 33547 72450 16632 81194 14873. The first three students in your sample have labels?
What are 400, 769, 335.
The most important advantage of experiments over observational studies is that
What is Experiments can give better evidence of causation?
Any difference between the sample result and the truth about the population that tends to occur in the same direction whenever you see this sampling method is called...
What is Bias?
How can you do to your observations or experiments make your statistical findings more accurate?
What is increase n = individuals?
Individuals who are humans
What is subjects?
A random sampling of different groups that have diversity within its group.
What is cluster sampling?
A researcher wishes to compare the effects of two fertilizers on the yield of soybeans. She has 20 plots of land available for the experiment, and she decides to use a matched pairs design with 10 pairs of plots. To carry out the random assignment for this design, the researcher should
What is Divide the 20 plots into 10 pairs, making the pairs as similar as possible, and then, for each pair, flip a coin to to assign the fertilizer to the 2 plots.
What is nonresponse?
A study of angina (pain due to low blood supply to the heart) compared bypass surgery, angioplasty, and use of drugs. The study looked at the medical records of thousands of angina patients whose doctors had chosen one of the treatments. It found that the average survival time of patients given drugs was the highest. What can we conclude?
What is We cannot conclude that drugs prolong life because this was an observational study.
What is confounding?
What is when you cannot tell whether the explanatory variable is affecting the response variable?
A TV station wishes to obtain information on the TV viewing habits in its market area. The market area contains one city of population 170,000, another city of 70,000, and four towns of about 5,000 inhabitants each. The station suspects that the viewing habits may be different in larger and smaller cities and in the rural areas. Which of the following sampling designs would give the type of information that the station requires?
What is A stratified sample from the cities and towns in the market area?
What is control?
What is Keeping all other variables that might affect the response the same for all groups?
What are the ways of collecting data with a bias?
What is convenience sample and voluntary response bias?
When an observed effect is so large that it would rarely occur by chance.
What is statistically significant?
You wonder if TV ads are more effective when they are longer or repeated more often or both. You prepare 30-second and 60-second ads for a camera. Your subjects all watch the same TV program, but you assign them at random to 4 groups. One group sees the 30-second ad once during the program; another sees it three times; the third group sees the 60-second ad once; and the last group sees the 60-second ad three times. Is this an observation or experiment? What are the factors?
What is experiment? What is two: length of ad & frequency of add?
What are three ways to randomly collect samples?
What is SRS (coin, paper in hat, calculator, internet, Table D)? What is stratified random sample? What is cluster sampling?
What are the 4 principles of experimental design?
What are Random Assignment, Comparison, Control, and Replication?
If you collect data randomly, can any biases occur to skew your data?
What is Yes?
What is undercoverage, nonresponse, wording of questions, response bias?
To limit the bias of doctor and/or patient.
What is Double-blind or single-blind?
What is necessary in every observation and experiment?
What is Randomness?
I want to know how many siblings HSA students have. I randomly sample 3 of each the freshmen, sophomores, juniors and seniors. Is this an SRS?
Elephants sometimes damage trees in Africa. It turns out that elephants dislike bees. They recognize beehives in areas where they are common and avoid them. If you were to design an experiment to test the theory of "Will elephant damage be less in trees with hives? Will even empty hives keep elephants away?" with 72 acadia trees, describe the experimental units, treatments and response variables.
What are the acadia trees?
What are placing either active beehives, empty beehives or nothing in the acadias?
What is Label your trees from 01 to 72. Using a Randomizer, assign the first 24 trees to the first treatment, and repeat for treatments 2 and 3?
You will vote for Trump again, right?
What is wording bias?
What is the difference between confidential and anonymity?