# Holt Middle School Math Course 2 2004 – Chapter 1

population a whole group you gather information about
sample a smaller part of the entire group you want to gather information about
random sample a representative sample where every member of the population has an equal chance of being chosen
mean the sum of the data values divided by the number of date items (often called the AVERAGE)
median the MIDDLE (or average of the two middle) value of data items arranged in order
mode the data value or values that occur the MOST
range the difference between the highest and least values in a set of data
outlier an EXTREME value that is much more or much less than the other values in a data set
frequency table a way to organize data into categories and groups
cumulative frequency a "running total" of frequencies in a category
bar graph a type of graph using bars to represent data values divided into equal intervals
histogram a bar graph that shows the frequency of data within equal intervals. There is no space between the bars.
double bar graph a bar graph used to compare two related sets of data
circle graph a type of graph showing how a set of data is divided into parts totaling 100% (also called a pie chart)
sector a "slice" of a circle graph representing one part of the data set
box-and-whisker plot a representation of the distribution of a data set divided into four equal parts, called quartiles
first quartile the median of the lower half of a set of data
second quartile the median of the data set
third quartile the median of the upper half of a set of data
lower extreme the minimum value in a data set
upper extreme the maximum value in a data set
line graph a graph with line segments connecting data points, used to show change over time
double line graph a graph that shows change over time for 2 sets of data
scatter plot a graph with 2 axes and points representing pairs of data values
positive correlation the values in both data sets increase at the same time
negative correlation the values in one data set increase as the values in the other set decrease
no correlation the values in two data sets show no pattern