STATS 121 EXAM 1 VERIFIED STUDY GUIDE
block - 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
boxplot - Answers - a plot of data that incorporates the maximum observation, the
minimum observation, the first quartile, the second quartile (median), and the third
quartile.
causation - Answers - changes in the explanatory variable directly affect the response
variable.
What is needed to verify causation? - Answers - Experiments
center - Answers - A summary number about which observations tend to cluster.
Measures of center include the mean and the median
continuous random variable - Answers - A variable that can take on any possible value.
control treatment - 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 - Answers - a sample type where the researcher contacts those
subjects that are readily available and does not use any random selection. The results
are almost always biased.
density curve - Answers - a mathematical model used to describe the overall pattern of
the distribution of a random variable
deviation - 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.
discrete random variable - Answers - a random variable that can only take on specific
values
distribution - Answers - a list of all possible values of a variable together with the
frequency (or probability) of each value
empirical (observational) probability - Answers - probability obtained from repeating an
experiment many times
, experiment - Answers - a study where treatments are deliberately imposed on the
individuals in the study before date is gathered in order to observe their responses to
the treatment
explanatory variable - Answers - a variable that may or may not explain the outcomes
(responses) of a study, also called INDEPENDENT or PREDICTOR variable
first quartile (Q1) - Answers - the median of a set of data less than the median of the
whole data set, 25% of data is less than it, 75% is greater than it
five number summary - Answers - minimum
Q1
median
Q3
maximum
..preferred numerical summary when data are very skewed or outliers are present
flagged value - Answers - a value that is a possible outlier
histogram - Answers - a graphical display of a quantitative data set; data are grouped
into intervals (usually of equal width) and a bar is drawn over each interval having
height proportional to frequency (or percentage) of values in the interval.
individual - Answers - each object or unit described or examined in a data set
inference - Answers - using results from a sample statistic value that splits the data in
half; the "middle" number after the data have been sorted
interquartile range (IQR) - Answers - the difference between Q3 and Q1; the length of
the box in the boxplot; contains 50% of the data.
interviewer bias - Answers - bias introduced into survey results by body language, voice
intonation, gender, race, etc. of an interviewer
law of large numbers - Answers - the fact that the average of observed values in a
sample ( x ) will tend to get closer to as the sample size increases
lurking variable - Answers - a variable that the researcher is not necessarily interested
in studying but which affects the relationship between the explanatory variable and the
response variable
match-pairs desgin - Answers - a design of experiment that combines matching of
subject or measurements with randomization. Either two measurements taken on each
unit (such as pre and post) OR measurements taken on two individuals matched by
some characteristics different from the explanatory variable and the response variable
block - 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
boxplot - Answers - a plot of data that incorporates the maximum observation, the
minimum observation, the first quartile, the second quartile (median), and the third
quartile.
causation - Answers - changes in the explanatory variable directly affect the response
variable.
What is needed to verify causation? - Answers - Experiments
center - Answers - A summary number about which observations tend to cluster.
Measures of center include the mean and the median
continuous random variable - Answers - A variable that can take on any possible value.
control treatment - 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 - Answers - a sample type where the researcher contacts those
subjects that are readily available and does not use any random selection. The results
are almost always biased.
density curve - Answers - a mathematical model used to describe the overall pattern of
the distribution of a random variable
deviation - 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.
discrete random variable - Answers - a random variable that can only take on specific
values
distribution - Answers - a list of all possible values of a variable together with the
frequency (or probability) of each value
empirical (observational) probability - Answers - probability obtained from repeating an
experiment many times
, experiment - Answers - a study where treatments are deliberately imposed on the
individuals in the study before date is gathered in order to observe their responses to
the treatment
explanatory variable - Answers - a variable that may or may not explain the outcomes
(responses) of a study, also called INDEPENDENT or PREDICTOR variable
first quartile (Q1) - Answers - the median of a set of data less than the median of the
whole data set, 25% of data is less than it, 75% is greater than it
five number summary - Answers - minimum
Q1
median
Q3
maximum
..preferred numerical summary when data are very skewed or outliers are present
flagged value - Answers - a value that is a possible outlier
histogram - Answers - a graphical display of a quantitative data set; data are grouped
into intervals (usually of equal width) and a bar is drawn over each interval having
height proportional to frequency (or percentage) of values in the interval.
individual - Answers - each object or unit described or examined in a data set
inference - Answers - using results from a sample statistic value that splits the data in
half; the "middle" number after the data have been sorted
interquartile range (IQR) - Answers - the difference between Q3 and Q1; the length of
the box in the boxplot; contains 50% of the data.
interviewer bias - Answers - bias introduced into survey results by body language, voice
intonation, gender, race, etc. of an interviewer
law of large numbers - Answers - the fact that the average of observed values in a
sample ( x ) will tend to get closer to as the sample size increases
lurking variable - Answers - a variable that the researcher is not necessarily interested
in studying but which affects the relationship between the explanatory variable and the
response variable
match-pairs desgin - Answers - a design of experiment that combines matching of
subject or measurements with randomization. Either two measurements taken on each
unit (such as pre and post) OR measurements taken on two individuals matched by
some characteristics different from the explanatory variable and the response variable
