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Producing Data By Bri Collins & Keely Smith (Observational Studies and…

- - - - Example: Which do you prefer, Duxbury Pizza’s fresh, delicious, homemade cheese pizza, or Papa Gino’s frozen, machine made, preservative filled cheese pizza?
      - Definition: Posing a question in a survey in a way to achieve a desired effect.
    - - Definition: When a responder gives a response they think/know the surveyor wants to hear.
      - Example: Mary Buckley asks a freshman on the swim team who she voted for for next years captains positions. The freshman is most likely going to say Mary whether they did or not.
    - - Definition: Bias when individuals in a survey are unwilling or unable to answer the survey, and these nonrespondents make an impact on the results of the survey.
      - Example: Surveys sent in the mail receive a significant amount of unanswered responses, as a result of people not answering and/or mailing back their responses, with because of inconvenience or disinterest. Assuming the nonrespondents follow the same trends as the respondents is incorrect and this is what introduces bias.
  - - - Advantages: Minimal knowledge of the study group is necessary, it is representative of the population as a whole, assessing the sampling error is fairly easy, and there the possibility for bias is eliminated.
      - Disadvantages: Time and money issues.
      - Definition: A sample chose randomly to avoid bias, unwanted effects, and uses tools such as a random number generator to pick its experimental units/subjects.
      - Example: At lacrosse practice, the team wants to scrimmage but wants to make the two teams fair. So, All the sticks are thrown in pile and one person picks sticks with their eyes closed one by one to determine two separate teams.
    - - Advantages: The survey will include the population as a whole, with people from each group.
      - Disadvantages: There is a lot of work in creating the groups, and the divisions of the groups have to be clear.
      - Definition: The researcher divides the total population into separate groups(strata). Then, a specific portion of each group is chosen to be part of the survey.
      - Example: At the airport, as people go through security there will be a survey given on how many times they have traveled out of the country this month. To survey every person would slow down the line too much. The security officer decides to make four groups: over 18 males, over 18 females, under 18 males, and under 18 females. He surveys 50 people from each of the strata in order to cover the who population.
    - - Advantages: Takes less time and money to conduct the survey.
      - Disadvantages: Can exclude specific groups of people from the survey. ex: No freshman have classes on the third floor.
      - Definition: The researcher divides the total population into separate groups, called clusters. Then, a simple random sample of clusters is selected from the population.
      - Example: In a high school, the principal wants to conduct a paper survey on the students' opinions of their teachers overall. With 1500 students in the school, this would take a lot of time and paper so the principal decides to do a cluster sample of only one floor of students chosen by a random sample.
  - - - Definition: People that volunteer to answer the question produced in the survey, so it is almost always biased.
      - Example: A radio DJ puts out an announcement that he is going to play a new song on the radio, and people can call after to say whether they liked the song or not. This is an example of Voluntary response sampling because it is probable that only people who strongly like or strongly dislike the new song
    - - Definition: A survey/sample made up of a group of people who are easy to reach.
      - Example: A student needs data for her AP Stats project, so she decides to go to the grocery store in town, because a lot of people go there every day and they are easy to ask.
    - - Example: I am running a survey to find out people's feelings on paying the co-curricular fee for families in Duxbury, for next year. However, I only send out the email to current high schoolers, and forget to include 8th graders, who will be in high school next year, when my survey is for next year.
      - Definition: A substantial amount of the population being surveyed isn’t present in the responses and statistical representation.
- - - - Definition: A member of the control group or the treatment group. A human is usually referred to as a subject in an experiment.
      - Example: An experimenter conducts an experiment, feeding dogs different kinds of dog foods to test their energy levels. The subjects are the dogs.
    - - Example: A scientist is testing the effects of adding glucose to the water of plants. They are all given 100mL of water, mixed with glucose. the levels of this experiment are 5 mg, 25 mg, and 50 mg of glucose.
      - Definition: An explanatory variable that is manipulated by the experimenter. Has two or more levels.
    - - Definition:When a person knows that they are being treated, it can improve a person’s condition simply because they believe it will help them. This is why having a control group is important in order to make sure that the improvement in the subjects’ conditions are not simply because of this placebo effect.
      - Example: A doctor is doing a medical trial on 20 patients to try a new medicine to cure their back pain. 10 patients receive the new drug, while 10 of them receive a fake drug, that has no effect, without knowing. 6 of the people who received the ineffective drug claim that their back pain has reduced, meaning that any results in the other group may not be from the drug.
    - - Definition: The variable that depends on another factor- the explanatory variable, to cause a change or a response to it.
      - Example: An experimenter is testing the affect of walking 30 minutes per day on weight loss. The response variable is how much weight the subjects lose.
    - - Definition: The substance or procedure studied in an experiment or study. The question is whether the treatment has an effect or causes improvement to a determined variable of focus. The combination of the two or more levels of the factors.
      - Example: Allison is a scientist studying ladybugs. She wants to know what kind of environment they like better: dry, wet, or somewhere in between. The 3 treatments of her experiment are the wet environment, dry environment, and the medium environment.
    - - Definition: the practice of not telling subjects if they are receiving a placebo. This is to make sure that subjects in the control and treatment groups experience the placebo effect equally.
        Double-blinding- When the experimenter does not know who was given which drug either, to reduce any bias or chance of accidentally telling the subjects.
      - Example: Dr. Grey is implementing an experiment on her patients with asthma. She has invented a new medicine thought to cure the disease. She has randomly selected 20 patients. 10 will receive the new medicine while 10 will receive a placebo. However, she tells all 20 patients that they are receiving the new medicine.
  - - - SRS- Using a Random number table, I will randomly assign 25 people to the treatment group, and 25 people to a control group. The subjects will be blinded and all 50 will be told that they are receiving the real drug.
        
        Factor A(25 subjects)- Control group- current drug
        
        Factor B(25 subjects)- Treatment group- new drug
      - Testing Response: The patients will give a number from 1 to 10 rating their pain at the beginning of the experiment, as well as the current frequency of migraine episodes per month. In 3 months they will be asked the same 2 questions, and in 6 months they will report their pain and number of migraines per month again. This data will be compared to see the effect of the treatment pain/frequency of migraines(response variables).