Nothing going on here, move along…

Basic Glossary

Quartiles– The middle values between the lowest number and the middle number (lower quartile) or the middle number and the highest number (upper quartile.)

Interquartile range– The upper quartile minus the lower quartile

Class interval– Data that is grouped into intervals (e.g. 10-20, 20-30), usually for the purpose of putting it into a graph.

Frequency– The number of times a particular class interval occurs.

Continuous variable– A piece of data that can have a percentage (e.g. It can take 2 and a 1/2 minutes to complete a task)

Discrete variable– A piece of data which has to be a whole number (e.g. The amount of right answers in a test must be 23 and cannot be 23.6)

Grouped frequency distribution– A list of the different varibles taken in a sample (e.g. 2,2,4,6,7,7,12,13,14,14)

Probability Trees– A diagram used to define the possiblities of getting a certain outcome. (see below)


Equation values of data

Mean– All the varibles added together and divided by the number of varibles there are.

Median– The middle piece of data in a set.

Mode– The most fashionable piece of data in a set.

Range– The highest value of a set minus the lowest value of the set.

Graph types and definitions

Bar graph– Used to show discrete information.

Histogram– Used to show continuous data, similar to a bar graph, except there is no space between the bars and it contains class intervals.

Line graph– Information is plotted on a graph, then those point are conectted with a continuous line.

Pictograph– An icon is used to display the set amounts of data.

Pie chart– A circle chart which shows the dataas slices as a pie, information is presented in percentages. 

Probability trees

                                              Heads (0.25) – 0.5×0.25= 2 heads odds

Heads (0.5)<

                                             Tails (0.25)


                                  Heads (0.25)

Tails (0.5)<

                                           Tails (0.25)

Probability trees are used to show the possibility of getting different data in a situation there are more than one outcome.

  • The first branches show the odds of getting each certain choice on the first coin toss. etc and have the chance of getting each option.


  • The second branches show the odds of getting the first choice and then the second choice. (e.g. tossing a head, then a tail or two heads)


  • There may be any amount of choices in the first branches, if the odds for each branch aren’t included, the odds are the number of branchs divisable into one (each branch gets an even odd and all added up they must equal 1.)


  • If you add all of the 0.**’s together in each column of the tree they must add up to 1. (e.g. 0.25+0.25+0.25+0.25=1)

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