DISCRETE

1
TYPES OF DATA
DISCRETE
CONTINUOUS
ordinal
nominal
interval
ratio
Q Is ratio data better than ordinal data?
2
NUMERICAL DATA
ORDERED ARRAY
FREQUENCY DISTRIBUTIONS
POLYGON (continuous)
HISTOGRAM (discrete)
OGIVE
f or Rf
cumRf
3
xL
xH
?cumRfN/A
?fn30
?Rf1
4
Steps to construct a grouped frequency
distribution

• Determine the size of the Class Interval.
• Always go to the resolution of the data.
• Ideally we want 10 class intervals (if not
  possible, we want more, but never less than 10
  intervals).
• Would like size (width) of each class interval to
  be in units of 1, 2, 3, 5, 10, 20, 30, 50, or
  multiples (factor of 10) of these values.
• Calculate the class interval size
• Calculate the range R
• Divide by 10 R/10
• Select the interval size nearest this value that
  will result in at least and as close to 10
  intervals as possible.

• Determine the Starting Point (first class
  interval) of the Frequency Distribution.
• The first number of the first class interval must
  be a multiple of the class interval size.
• The first interval must include the lowest number
  or value in the data set.