STA 270 Exam #1
Questions and Complete
Solutions Graded A+
Statistics - Answer: the scientific discipline that provides methods to help us make sense of data
Variable - Answer: any characteristic whose value may change from individual or object to another ex.
weight, height, IQ...
Population - Answer: the entire collection of individuals or objects above which information is desired
Sample - Answer: a subset of the population selected for study
Descriptive Statistics - Answer: a branch of statistics that includes methods for organizing and
summarizing data
Inferential Statistics - Answer: a branch of statistics that involve generalizing from a sample to a
population from which the sample was selected and assessing the reliability of such generalization
Categorical Data - Answer: classified into categories ex. hair color
Nominal - Answer: order is not important, one is not better than the other ex. gender
Ordinal - Answer: order is important ex. letter grade, marathon results
Numerical Data - Answer: measured on a numerical scale ex. GPA, height
, Discrete - Answer: distinct values with gaps in between ex. # of siblings, GPA
Continuous - Answer: takes any value in an interval on a number line, there are no gaps between
possible values ex. time, weight, age
Univariate - Answer: collect observations from a single variable ex. height
Multivariate - Answer: collect observations from 2 or more variables ex. height & weight & age
Bivariate - Answer: collect observations from 2 variables, special multivariate data set ex. height &
weight
Data - Answer: observations made on either a single variable or simultaneously on two or more variables
Observational Study - Answer: interested in answering questions about characteristics of a population or
comparing such characteristics in two or more well-defined populations ex. determining whether gender
and attitude toward abortion are related
Experimental Study - Answer: interested in answering questions such as "what is the effect of...?" "what
happens when...?"
Selection Bias - Answer: intentionally leave out certain parts of the population bias as a result of
systematic exclusion of some part of the population ex. conducting a survey of NAU students only on the
south campus
Measurement/Response Bias - Answer: bias as a result of the method of observation tends to produce
values that differ from the true value ex. the tendency of people not to be completely honest when
asked in person about illegal behavior or unpopular beliefs
Non-response Bias - Answer: bias as a result of data not obtained from all individuals in the sample
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