axis
 a line drawn through the center of a figure
scale  a sequence of marks, usually along a line, used
in making measurements
proportional  one variable is proportional to another if
the ration of corresponding values remains constant
interpolation  to estimate a value by following a
pattern and staying within the values already known
extrapolation  to estimate a value by following a
pattern and going beyond the values already known
discreet variable  have measurements that are distinct,
periodic, and unconnected between data points (e.g. the distance an athlete throws a
discus)
continuous variable  measurements are uninterrupted and connected
between data points (e.g. growth of a plant)
scatter plot  a graph that relates data from two
different sets
line of best fit (trend line)  A line on a scatter plot
which can be drawn near the points to more clearly show the trend between two sets of data
trend  relationship between two sets of data. The trend
will show a positive correlation, a negative correlation, or no correlation.
positive correlation both sets of data increase together
negative correlation one set of data decreases as the
other set of data increases
no correlation  the two data sets are not related.
weak correlation  when the data is not clustered along
an obvious line
strong correlation  when the data is clustered along an
obvious line ( can be positive or negative)
lower extreme  minimum data value
upper extreme  maximum data value
range  upper extreme minus lower extreme
cluster  a particular segment of the population
gaps  spaces in the data set without a segment of the
population
outlier  a point separted from the main body of the data
central tendency  point within the range about which the rest of the
data is considered balanced. The three common measures of central tendency are:
 mode  the most frequently observed value of the measurements in the sample.
There can be more than one mode or no mode.
 mean  the sum of all the results included in the sample divided by the number of
observations
 median  the middle value of all the numbers in the sample.
 for an even number of values, the median is the average of the middle two values
 for an odd number of values, the median is the middle of the all of the values.
lower quartile  separates the first 25% of the distribution from the
remaining 75%.
upper quartile  separates the first 75% of the distribution from the
remaining 25%.
Picture the Parts
Example for an Odd Number of Data Items
number of data items (N) 
15 
upper extreme 
98 
lower extreme 
5 
range 
98  5 = 93 
median (MED) 
56 
lower quartile (Q1) 
50 
upper quartile (Q3) 
62 
Example for an Even Number of Data Items
number of data items (N) 
16 
upper extreme 
98 
lower extreme 
5 
range 
98  5 = 93 
median (MED) 
(50 + 51)/2 = 50.5 
lower quartile (Q1) 
49 
upper quartile (Q3) 
82 

