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Statistics Test 1
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Gravity
Terms in this set (44)
variation
refers to differences in a characteristic among individuals or items; fluctuation over time
individuals
corresponds to rows in data table; subjects/objects of the population of interest
observation
corresponds to a cell in a data table; an observation in a data set refers to the observed value of a variable on a specific individual
variable
corresponds to columns in data table; any characteristic of an individual that we are interested in.
categorical variable
qualitative (qualities) variable; individuals can be placed into one of several distinct categories
quantitative variable
quantities (numbers) variable; take on numerical values
nominal
order not meaningful; ex: city your born in
ordinal
order may be meaningful; has some natural order to it; ex: year in school, grades
discrete
values correspond to isolated points on a number line; typically counts; ex: number of siblings, pets you own
continuous
values form an entire interval on the number line; ex: height, weight, age, temperature
Population
entire group of individuals or subjects about which we want to gain information
process
a component of a system that has inputs and outputs
sample
a part of a population from which we obtain information in order to draw conclusions about the entire population
Sample Statistic
any numerical summary describing a sample
Population parameter
any numerical summary describing a population
representative sample
a sample that is a mini picture of the population; eliminate bias; get random sample
Simple Random Sample
every combination of n individuals from the population has an equal chance of selection; n is used to represent the sample size
Convenience sampling
the selection of units from the population is based on easy availability and/or accessibility; conducting a survey in front of the library about the library; often yield bias responses
voluntary response sample
consists of people who chose to participate by responding to a general appeal; online polls, tv polls, magazine polls; often yield bias responses
precision
all data points are very close to each other; related to variability
accuracy
all data points are close to expected data points; related to minimizing bias
observational studies
simply observing what happens; can't prove causation; not assigning individuals to certain things
retrospective study
looking at past results or historical data
prospective study
researchers identify subjects in advance and record results/events as they happen
experiments
can prove causation; performing an experiment; assigning individuals to certain treatments
explanatory variables
explains changes in the responsefactors
response variable
what we want to learn about
factors
an explanatory variable that the experimenter is actively manipulating
levels
specific values the experimenter is actively maniupulating
treatment
combinations of specific levels from all factors
experimental units
individual to whom you apply a treatment
control group
experimental units assigned to a baseline treatment
placebo
a null treatment known to have no effect
placebo effect
tendency of many human subjects to show response even when administered a placebo
blinding
the researcher disguises the treatment
descriptive statistics
the collection, presentation and description of data in form of graphs, tables, and numerical summaries that provide meaningful information about the data
inferential statistics
the interpretation of data as well as drawing conclusions and making generalizations based on data for a larger group of subjects
distribution
(of a variance) contains all passable outcomes/responses and how often each response occurred.
relative frequency
summarize categorical variables; sample statistic; count for category divided by total # of responses
proportion
two outcomes are success or failure; #success divided by sample size; ex of sample statistic
bar charts
categorical variable; shows the amount of data that belong to each category as proportionately sized rectangular areas
contingency table
summarize the distribution of two categorical variables simultaneously
histograms
summarizes observations from a quantitative variable
measuring center values
three common measures of the center are: mean, median, mode
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