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Unit 3 (Survey Example (Questions (Favorite genre? (Rock, Pop, Hip-hop,…
Unit 3
Survey Example
Questions
Favorite genre?
Rock, Pop, Hip-hop, Country, Clasical
Favorite era of music?
70's, 80's, 90's, 00's, 10's
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Vacab
Experimental Units: The physical entity of an experiment that can describe conditions of a variable. Example: different types of fertilizer used on a plant.
Explanatory Variables: An independent variable manipulated by the experimenter. Example: Different amounts of water given to a plant.
Treatments: Something given to make a change. Then analyzed to figure results. Example: A medication given to a person.
Response Variables: A variable of interest that is chosen. More attention is pt on this variable. Example: People who score high on a test.
Samples and Surveys
Sampling Error
A sampling error is an error where a surveyor does not select a sample that does not represent the entire population
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Convenience Sampling: A type of non-sampling method. Made up of people who are easy to reach. This is a narrow range of people. Example: Interviews on one area of a street
Voluntary Response Sampling: Made up of volunteers. These are most always biased. The people who volunteer usually sway one direction because they are the ones who care. Example: People who call into a radio show
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Non-sampling Error
Wording Bias
Choice of words and phrases in a question is critical in expressing the meaning and intent of the question. Small wording differences can substantially affect the answers people provide.
Non-response
Bias that results when respondents differ in meaningful ways from non-respondents. Often a problem with mall surveys, where the response rate can be very low.
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Bias
Positive - Observed affect that is higher than the true value. Negative - Observed affect that is lower than the true average
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Good Sampling Techniques
SRS (Simple Random Sample): A group of randomly selected sample of randomly selected individuals chosen from an area with a larger population. Example: 25 people are chosen from a hat out of a group of 250. Advantage: it is much faster Disadvantage: you're only taking a fraction of the data.
Cluster Sampling: A sampling technique used when natural but heterogeneous groupings are evident in a statistical population. Example: dividing a state into all of its different cities.Advantage: It's easier to divide it up. Disadvantage: It is less precise.
Stratified SRS: (Stratified Random Sampling) is a sampling method that involves division into smaller groups known as strata. The strata are formed based on members' shared attributes. Advantage: you can get a general depiction. Disadvantage: It is not very precise.
Placebo Effect
Effects of something taking place with the expectation that something is going to happen, when in reality, it is only the person's brain creating the effect they are feeling.
Example: A medication is being tested. One half of the test subjects take the real medication. The other half take a fake medication that has no effect. Both groups are told that they are taking the real medication. Both groups say that they notice a difference in how they are feeling.
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Lurking Variable
Example: Comparing watermelon sales to bathing suit sales in the summer. They can both have the same results but they are completely independent of each other.
Two or more variables that have the same affect but they are unrelated. Comparing lurking variables will lead to a contradiction of results.
Blinding Effect
An Experiment where the conditions are hidden from the subjects. The subjects have no idea which treatment they are receiving if any at all. Reduces chance of the placebo effect taking place.
Example: A medication is being tested. The subjects are given the medication without knowing what it does. Then the results of the reported effects are collected.