| Population (population of intrest) | An entire group of individuals that you're interested in learning about |
| sample | A smaller group of specific individuals selected from the population to study |
| population of parameter of interest | A characteristic or measurement of the populations that you're interested in learning about |
| sampling frame | A group of possible individuals you're creating a sample from |
| census | When you survey the entire population instead of just a sample |
| observation study | A study based on data in which no treatments are assigned |
| experiment | Similar to observational study, but treatments are randomly assigned. Causation can be determined from experiments. |
| convenience sample | A non-random sampling method that can only include individuals who are convenient/easy to sample, such as friends or the first person we see. Biased and not representative of the entire population. |
| voluntary response sample | A non- random sampling method that only includes individual who choose to call-in, participate, etc. Biased and not representative of the entire population. |
| random sample | a sampling method that use random chance to select individuals for a sample, which has no bias |
| simple random sample | using a random process to choose a group from the population so that every individual and every group of individuals is equally likely to be chosen |
| sampling variability | the concept that the results from different samples won't be the exact same due to the random processes. |
| margin of error | how far off our estimated value from a sample might be compared to the true value for a population |
| bias | If a sampling method is biased, then something is wrong with how we collect data. This creates baddata that is not representative of the population. |
| undercoverage bias | When the data collection process is set up in a way such that some members of a population cannot or are less likely to be included in a sample |
| nonresponse bias | when an individual is part of a survey/ sample but does not respond or chooses not responds. |
| response bias | factors that influences individuals to provide false or inaccurate responses. Examples: wording of a question, who is asking the questions, lying, etc |
| placebo effect | when someone receives a "fake" treatment and it actually helps them even through its not supposed to |
| control group | a group that receives a placebo or no treatment, used as a baseline for comparison |
| single blind | when the subjects/experimental units do not want the treamnets they are receiving |
| confounding variables | A variable that influences both the explanatory and response variables, which may affect proving causation |
| Purpose of random assignment | To show causation from an experiment |
| Purpose of random sample | To generalize the results |
