ch 8 vocab Flashcards
the mode is
the value or values that occur most often
weighted average of a data set
gives greater importance, or weight, to some values in the set than to others
to find a weighted average,
multiply each value by its weight
the expected value is
the weighted average of the possible outcomes
the weight for each outcome is its
probability
a box-and-whisker plot
shows the spread of a data set
the interquartile range is the
difference between the 1st and 3rd quartiles
a measure of variation is
a value that describes the spread of a data set
the variance is
the average of the squared differences from the mean
standard deviation is
the square root of the variance and is one of the most common and useful measures of variation
an outlier is
an extreme value that is much less than or much greater than the other data values
a population is
the entire group of people or objects that you want information about
a census is
a survey of an entire population
a sample is
part of the population
random sample (probability sample) is
when every member of a population has an equal chance of being selected for a sample
some non-random samples are:
convenience samples and self-selected samples
a biased sample is
a sample that that may not be representative of a population
in a biased sample, the population can be
underrepresented or overrepresented
a statistic is
a number that describes a sample
a parameter is
a number that describes a population
you can use a statistic from a survey to
estimate a parameter
individuals are
people, animals, or objects that are described by data
an experiment
imposes a treatment on individuals to collect data on their response to the treatment
an observational study
observes individuals and measures variables without controlling the individuals or their environment in any way
in a controlled experiment,
two groups are studied under conditions that are identical except for one variable
treatment group
receives treatment
control group
used for comparison, does not receive treatment
in a randomized comparative experiment,
the individuals are assigned to the control group or the treatment group at random, in order to minimize bias
reliable experiments can be
repeated and can be expected to produce similar results each time
hypothesis testing is
used to determine whether the difference in two groups is likely to be caused by chance
null hypothesis states
that there is no difference between the two groups being tested
mean is the
sum of the values in the set divided by the number of values. often represented as x repeating
the median is
the middle value or the mean of the two middle values when the set is ordered numerically
Null hypothesis rejected
The difference is too large
Z-test
When the sample contains at least 30 individuals the z-test can be used to reject the null hypothesis if the z value is too large
(section 8-5) simple random sample: members are chosen using a method that gives everyone an
equally likely chance of being selected
(section 8-5) systematic sample: members are chosen using a pattern, such as
selecting every other person
(section 8-5) stratified sample: the population is first divided into groups. then members are
randomly chosen from each group
(section 8-5) cluster sample: the population is first divided into groups. a sample of the groups is
randomly chosen. all members of the chosen groups are surveyed.
(section 8-5) convenience sample: members are chosen because they are
easily accessible
(section 8-5) self-selected sample: members volunteer to
participate
(section 8-5) a probability sample is a sample where every member of the population being sampled has a
nonzero probability of being selected
(section 8-5) the margin of error of a random sample defines an
interval, centered on the sample percent, in which the population percent is most likely to lie
(section 8-6) binomial theorem: patter that can help you
expand any binomial
(section 8-6) binomial experiment consists of n independent trials whose
outcomes are either successes or failures
(section 8-6) binomial probability: in a binomial experiment, the probability of r successes (0
P(r) = nCr x p^r q^n-r
(Section 8-8) the expected value (EV) is the weighted average of the numerical
outcomes of a probability experiment
