STAT 503 Quiz 1 Questions and Answers Graded A+
Randomization - Answer-allows an experiment to establish a cause-and-effect relationship; under random assignment the groups shouldn't differ significantly with respect to potential confounding variables; randomization of treatments establish a clear...
STAT 503 Quiz 1 Questions
and Answers Graded A+
Randomization - Answer-allows an experiment to establish a cause-and-effect
relationship; under random assignment the groups shouldn't differ significantly with
respect to potential confounding variables; randomization of treatments establish a
clearer causal relationship and controls for all lurking variables as well as helps to rid
bias
frequency - Answer-the count of occurrences
frequency distribution - Answer-describes the number of times each value of a variable
occurs in a sample; (of a categorical variable) lists the categories and gives the
count/frequency/percent of individuals who fall into each category
probability distribution - Answer-the distribution of a variable in the whole population
bar graph - Answer-includes spaces with no meanings, the height of the bars represents
the count, separated into categories on the x-axis and the counts are on the y-axis
pie chart - Answer-uses slices that are sized by the frequency or relative frequency for
the categories
Histogram - Answer-data that is split into consecutive intervals (bins); includes no
spaces between bars, the area of the bars represents the amount, usually in intervals,
gap means no data for that interval
Outlier - Answer-not consistent with the majority of the data
bin - Answer-the consecutive intervals (usually of equal width) for a histogram
association - Answer-two variables that are statistically related if knowing the value of
one variable tells us something about the distribution of the other variable (correlation)
confounding variables - Answer-an unmeasured variable that changes in tandem with
one or more of the measured variables
, observational study - Answer-the assignment of treatments is not made by the
researcher or the values of the explanatory variable are not randomly assigned; data
can show association but not cause-and-effect relationships
theoretical probability distribution - Answer-used to approximate the real probability
distribution since it is almost never known for a population in nature
normal distribution - Answer-a bell-shaped curve, describing the spread of a
characteristic throughout a population, usually featuring some symmetry
Fitting a model - Answer-with having data from a sample, statistics can be used to
approximate the parameters
Data - Answer-the measurements of one or more variables made on a sample of
individuals
treatment variable - Answer-also called the explanatory variable; the one manipulated
by the researcher
statistical population - Answer-a group of things we want to draw a conclusion about
statistical sample - Answer-a subset of the population; smaller group of individuals of
the population we select to actually collect data on
biological sample - Answer-a specimen, usually a physical object collected from an
organism or ecosystem (one statistical sample can be made up of multiple biological
samples)
ordinal variable - Answer-levels of categorical variables that are inherently ranked and
can be ordered
nominal variable - Answer-categorical variables for which the categories do not have a
natural ordering or ranking
relative frequency - Answer-A ratio that compares the frequency of each category to the
total; equal to proportion; the proportion of observations having a given measurement,
calculated as the frequency divided by the total number of observations
population - Answer-all the individual units of interest
parameter - Answer-a population quantity that is used to describe some characteristics
of a population; cannot be measured
sample - Answer-a smaller group selected from the population that we usually observe
and collect data on
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