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STA 126 TEST 1 Questions and Complete Solutions Graded A+
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STA 126 TEST 1 Questions and Complete Solutions Graded A+
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STA 126 TEST 1Questions and Complete
Solutions Graded A+
Statistics - Answer: Collection of methods for planning experiments, obtaining data, organizing,
summarizing, presenting, analyzing, interpreting, and drawing conclusions based on data.
Data - Answer: Fact or proposition used to draw a conclusion or make a decision
Response variable - Answer: a variable that measures an outcome or result of a study
Explanatory Variable - Answer: A variable that helps explain or influences changes in a response
variable; In research, we want to determine how varying the amount of an explanatory variable affects
the value of a response variable.
Observational Study - Answer: measures the value of the response variable without attempting to
influence the value of either the response or explanatory variables. That is, in an observational study,
the researcher observes the behavior of the individuals (in the study) without trying to influence the
outcome of the study.
Designed Experiment - Answer: a researcher assigns the individuals in a study to a certain group,
intentionally changes the value of the explanatory variable, and then records the value of the response
variable for each group
cofounding variable - Answer: in an experiment, a factor other than the independent variable that might
produce an effect; an explanatory variable that was considered in a study whose effect cannot be
distinguished from a second explanatory variable in the study.
, lurking variable - Answer: an explanatory variable that was NOT considered in a study, but that affects
the value of the response variable in the study. In addition, lurking variables are typically related to any
explanatory variables considered in the study.
Cross-sectional study - Answer: Observational studies that collect information about individuals at a
specific point in time, or over a very short period of time.
case-control study - Answer: These studies are retrospective, meaning that they require individuals to
look back in time or require the researcher to look at existing records. In case-control studies, individuals
who have certain characteristics are matched with those that do not
Cohort study - Answer: A cohort study first identifies a group of individuals to participate in the study
(the cohort). The cohort is then observed over a long period of time. Over this time period,
characteristics about the individuals are recorded. Because the data is collected over time, cohort
studies are prospective
Census - Answer: a list of all individuals in a population along with certain characteristics of each
individual.
Random sampling - Answer: the process of using chance to select individuals from a population to be
included in the sample
simple random sample - Answer: A sample of size n selected from the population in such a way that
each possible sample of size n has an equal chance of being selected.
stratified sample - Answer: obtained by separating the population into nonoverlapping groups called
strata and then obtaining a simple random sample from each stratum. The individuals within each
stratum should be homogeneous (or similar) in some way.
systematic sample - Answer: obtained by selecting every kth individual from the population. The first
individual selected is a random number between 1 and k.
steps in systematic sampling - Answer: 1. If possible, approximate N (population size)
2. Determine n (sample size)
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