stats - unit 1

• stats (plural) - data points that we are computing
• stats (singular) - the science of collecting data
• population - entire group being studied, that we will apply the stats to
• sample - a section of the population that we take the data from
• raw data - individual answers to the survey questions
• goal -> sample -> raw data -> sample stats -> population parameter/characteristics
• margin of error - the difference between the true value of the population parameter and the estimated value
• confidence interval - fluctuation in sample statistic based on the margin of error
• representative - sample has all the necessary characteristics of the population
• bias - a certain outcome is favored, or the sample isn't representative of the population
• random sampling - everyone has an equal chance of being selected
• systematic sampling - there is a method in choosing subjects, ex every 10th person
• there is no 'best' sampling method, it is situational
• convenience sampling - subjects are chosen based on the ease for the statisticians
• cluster sampling - separating the population into groups, choosing a random group, and surveying everyone within that group
• stratified sampling - forming subgroups again, but a set number of people are chosen randomly from each subgroup
• population parameter - describes a characteristic of the population
• sample statistic - numbers describing characteristics of the sample
• a margin of error is used to describe a range of values likely to contain a population parameter, added/subtracted from the sample statistic to establish a confidence interval. this is used to estimate the population parameter
• census - collects data from all members of a population
• subjects and participation aren't the same, one implies choice
• there are two types of statistical studies, observational and experimental
• observational study - watch the sample/population
• experimental study - altering of variables to test for a specific outcome
• variables - any quantity that can change
• variables of interest - quantities the study is looking to measure
• explanatory variable - a quantity that explains an effect, ex independent variable
• response variable - quantity that responds to changes in the explanatory variable, ex dependent variable
• in observational studies, you can use past and future data
• retrospective study - past data
• prospective study - future data
• experimental/treatment group - receives treatment in an experiment
• control group - doesn't receive the treatment in an experiment, might receive a placebo
• confounding variables - variables that affect the reliability of the data
• placebo effect - people improve because they believe they are receiving the treatment (they are not)
• experimenter effects - researcher inadvertently influences the results of a trial
• blinding - keeping people in the dark about who is in which group
• single blind - only participants don't know the group
• double blind - both participants and researchers don't know who's in which group
• there are two types of data, qualitative and quantitative