biased sample
A sample that is not representative of a population.
box plot
A diagram that divides a set of data into four parts using the median and quartiles. A box is drawn around the quartile values and whiskers extend from each quartile to the extreme data points.
complement
One of two parts of a probability making a whole. Two events are complementary if one or the other must happen, but they cannot happen at the same time. For example, when you roll a die the die must land on an even or an odd number but no both. The sum of the probability of an event and its complement is 1 or 100%.
compound event
Two or more simple events.
convenience sample
A sample which includes members of the population that are easily accessed. Ex. The first 10 students in the cafeteria line.
distribution
Shows the arrangement of data values. You can compare two numerical data sets by comparing the shape of their distributions.
double box plot
Two box plots graphed on the same number line.
experimental probability
What actually occurs in a probability experiment.
first quartile
For a data set with median M, the first quartile is the median of the data values less than M.
Fundamental Counting Principle
If event M can occur in m ways and is followed event N that can occur in n ways, then the event M followed by N can occur in mn ways. Ex. If there are 4 possible sizes for fish tanks and 3 possible shapes, then there are 4 3 or 12 possible fish tanks.
interquartile range
The range of the middle half of a set of data. It is the difference between the first quartile and the third quartile.
mean absolute deviation
The average distance between each data value and the mean.
measures of center
For a list of numerical data, numbers that can represent the center of the data. Ex. Mean, Median and Mode.
measures of variability
Used to describe the distribution of statistical data.Examples are range, variance and standard deviation.
outcome
Possible result of a probability experiment.
outliers
Data that are more than 1.5 times the interquartile range beyond the quartiles.
population
A larger group used in statistical analysis.
probability
The ratio of the number of ways a certain event can occur to the number of possible outcomes. P(event) = # favorable outcomes/# possible outcomes
quartile
The values that divide a set of data into four equal parts.
random
Outcomes occur at random if each outcome is equally likely to occur.
range
The difference between the highest and lowest scores in a distribution. It describes whether the data are spread out of clustered together.
relative frequency
The ratio of the number of experimental successes to the number of experimental attempts.
sample
A subgroup or subset of a population used to represent the whole population.
sample space
The set of all possible outcomes.
simple event
One outcome or a collection of outcomes.
simple random sample
A sample where each item or person in the population is as likely to be chosen as any other. Ex. Thirty student ID numbers are randomly selected by a computer.
simulation
A way of modeling a problem situation or event that would be too difficult or impractical to actually perform.
statistics
The branch of mathematics that deals with collecting, organizing, and interpreting data.
stratified random sample
The population is divided into similar, non-overlapping groups. A simple random sample is then selected from each group. Ex. A population of election districts can be separated into urban, suburban, and rural strata.
systematic random sample
A sampling method in which the items or people are selected according to a specific time or item interval. Ex. Every 20 minutes a customer is chosen, or every 10th customer in line is chosen.
theoretical probability
What should occur in a probability experiment.
third quartile
For a data set with median, M, the third quartile is is the median of the data values greater than M.
tree diagram
A diagram used to show the total number of possible outcomes.
unbiased sample
A random sample that is representative of a larger sample.
uniform probability model
A model in which each outcome has a equal probability of occurring.
visual overlap
If distributions have similar variation than this will be a visual demonstration that compares their centers to their variation, or spread.
voluntary response sample
A sample which involves only those who want to participate in the sampling. Ex. The principal sent an e-mail to graduating seniors asking them where to hold commencement and they voted through an on-line poll.