is the proportion or percent of observations within a category and is found using the formula relative frequency = frequency/ sum of all frequencies
relative frequency
lists each category of data together with the relative frequency
relative frequency distribution
constructed by labeling each category of data on either the horizontal or vertical axis and the frequency or relative frequency of the category on the other axis. rectangles of equal width are drawn for each category. the height of each rectangle represen
bar graph
bar graph whose bars are drawn in decreasing order of frequency or relative frequency
pareto chart
circle divided into sectors. each sector represents a category of data. the area of each sector is proportional to the frequency of the category.
pie chart
raw data are data that is not
organized
in a relative frequency distribution, the relative frequencies add up to
1
classes
categories of data
constructed by drawing rectangles for each class of data. the height of each rectangle is the frequency or relative frequency of the class. the width of each rectangle is the same and the rectangles touch each other.
histogram
lower class limit
smallest value within the class
upper class limit
largest value within the class
the difference between consecutive lower class limits
class width
open ended
table is this if the first class has no lower class limit or th least class has no upper class limit
class width =
largest data value - smallest data value / number of classes
stem ad leaf plot
represents quantitative data graphically. digits to the left of the rightmost digit to form the stem. each rightmost digit forms a leaf.
split stems
data appear rather bunched. rather than using one stem for the class of data 10-19 we could use two stems one for the 10-14 and the second for 15-19 interval
dot plot
placing each observation horizontally in increasing order and placing a dot above the observation each time it is observed
uniform distribution
frequency of each value of the variable is evenly spread out across the values of the variable
bell shaped distribution
highest frequency occurs in the middle and frequencies tail of to the left and right of the middle
skewed right
tail to the right of the peak is longer than the tail to the left of the peak
skewed left
tail to the left of the peak is longer than the tail to the right of the peak
time series data
if the value of a variable is measured at different points in time, the eta are referred to as this
time series plot
obtained by plotting the time in which a variable is measured on the horizontal axis and the corresponding value of the variable on the vertical axis. line segments are then drawn connecting the points.