STAT 121 BYU Exam 1 Questions With Complete Solutions
2 number summary Correct Answers - uses mean and SD
block Correct Answers A group of experimental units sharing
some common characteristic. In a randomized complete block
design, random allocation of treatments is carried out separately
within each group (a group of males and a group of females)
boxplot characteristics Correct Answers 1. central box spans
interquartile range
2. line in box marks median 3. right whisker extends from box to
largest non-flagged value
4. left whisker extends from box to smallest non-flagged value
5. flagged value represented by asterisks
6. boxplot can be horizontal or vertical
boxplot: Correct Answers A plot of data that incorporates the
maximum observation, the minimum observation, the first
quartile, the second quartile (median), and the third quartile.
- Idea:
• high density of data between Q1 and Q3
• low density between min and Q1
• low density between Q3 and max
• represent density by thickness of box
• for simplicity, 2 densities/thicknesses
causation Correct Answers Changes in the explanatory variable
directly affect the response variable. Experiments are needed to
verify causation
,center of a histogram Correct Answers - like a see-saw: you
want balance
- close to the median
- where does the midpoint seem to be along the horizontal axis?
center: Correct Answers A summary number about which
observations tend to cluster. Measures of center include the
mean and the median
components of the standard normal distribution Correct Answers
• normal density curve with µ = 0 and σ = 1
• area under curve = proportion/percentage/probability
• areas under curve for standard normal completely
specified in the table of standard normal probabilities
• consists of z-scores or standardized scores with mean
µ = 0 and σ = 1
continuous random variable Correct Answers a variable that can
take on any possible value
control treatment Correct Answers A treatment where no
experimental condition is applied to the units in order to
determine whether the active treatments affect the response.
This enables the researcher to "control" for lurking variables
convenience sample Correct Answers A sample type where the
researcher contacts those subjects who are readily available and
does not use any random selection. The results are almost
always biased.
, density curve Correct Answers A mathematical model used to
describe the overall pattern of the distribution of a random
variable.
deviation Correct Answers The difference (distance) between
an observation and the mean of all the observations in a data set,
or the difference between an observation and the corresponding
regression model estimate.
difference between density curves and histograms Correct
Answers - The notation for mean and standard deviation is
different for density curves (populations) than for histograms
(samples
discrete categorical Correct Answers e.g. college major
discrete quantitative Correct Answers e.g. number of persons
living in a household
discrete random variable Correct Answers A random variable
that can only take on certain specific values
distribution Correct Answers A list of all possible values of a
variable together with the frequency (or probability)
of each value
distribution of a variable Correct Answers summary of data one
variable at a time
- what values does the variable take?
- how often do these values occur?
2 number summary Correct Answers - uses mean and SD
block Correct Answers A group of experimental units sharing
some common characteristic. In a randomized complete block
design, random allocation of treatments is carried out separately
within each group (a group of males and a group of females)
boxplot characteristics Correct Answers 1. central box spans
interquartile range
2. line in box marks median 3. right whisker extends from box to
largest non-flagged value
4. left whisker extends from box to smallest non-flagged value
5. flagged value represented by asterisks
6. boxplot can be horizontal or vertical
boxplot: Correct Answers A plot of data that incorporates the
maximum observation, the minimum observation, the first
quartile, the second quartile (median), and the third quartile.
- Idea:
• high density of data between Q1 and Q3
• low density between min and Q1
• low density between Q3 and max
• represent density by thickness of box
• for simplicity, 2 densities/thicknesses
causation Correct Answers Changes in the explanatory variable
directly affect the response variable. Experiments are needed to
verify causation
,center of a histogram Correct Answers - like a see-saw: you
want balance
- close to the median
- where does the midpoint seem to be along the horizontal axis?
center: Correct Answers A summary number about which
observations tend to cluster. Measures of center include the
mean and the median
components of the standard normal distribution Correct Answers
• normal density curve with µ = 0 and σ = 1
• area under curve = proportion/percentage/probability
• areas under curve for standard normal completely
specified in the table of standard normal probabilities
• consists of z-scores or standardized scores with mean
µ = 0 and σ = 1
continuous random variable Correct Answers a variable that can
take on any possible value
control treatment Correct Answers A treatment where no
experimental condition is applied to the units in order to
determine whether the active treatments affect the response.
This enables the researcher to "control" for lurking variables
convenience sample Correct Answers A sample type where the
researcher contacts those subjects who are readily available and
does not use any random selection. The results are almost
always biased.
, density curve Correct Answers A mathematical model used to
describe the overall pattern of the distribution of a random
variable.
deviation Correct Answers The difference (distance) between
an observation and the mean of all the observations in a data set,
or the difference between an observation and the corresponding
regression model estimate.
difference between density curves and histograms Correct
Answers - The notation for mean and standard deviation is
different for density curves (populations) than for histograms
(samples
discrete categorical Correct Answers e.g. college major
discrete quantitative Correct Answers e.g. number of persons
living in a household
discrete random variable Correct Answers A random variable
that can only take on certain specific values
distribution Correct Answers A list of all possible values of a
variable together with the frequency (or probability)
of each value
distribution of a variable Correct Answers summary of data one
variable at a time
- what values does the variable take?
- how often do these values occur?
