Data presentation                      Prepared by                      Assis. Prof.                    Namir G. Al-Tawil
The ordered array It is the first step in the process of data  organization. An ordered array is a listing of values of ...
The frequency distribution  One  of the ways of data summarization.  To group a set of observations, we   select a set o...
The frequency distribution, cont. Sturge’s   rule (formula):  K = 1 + 3.322 (log10 n)  K = No. of class intervals. n = sa...
The frequency distribution, cont. The  width (W) of class interval, in general,  is equal, but sometimes this is not poss...
Example of a frequency distributiontable of 169 subjects of differentagesClass      Frequency Cumulative Relative Cumulati...
90                 80                 70                 60                 50Success rate %                 40           ...
6            5            4frequency            3            2            1            0                17.5 20 22.5 25 27...
70            60            50            40frequency            30            20            10            0              ...
Males, 150, 33%Females, 300, 67%                Figure 1. Distribution of sample by sex
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
Stat 2 data presentation2
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Stat 2 data presentation2

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Stat 2 data presentation2

  1. 1. Data presentation Prepared by Assis. Prof. Namir G. Al-Tawil
  2. 2. The ordered array It is the first step in the process of data organization. An ordered array is a listing of values of a collection in order of magnitude from the smallest value to the largest value. It enables one to determine quickly the value of the smallest measurement, and the value of the largest measurement, and enable one to determine roughly the proportion of people lying below or above certain value.
  3. 3. The frequency distribution  One of the ways of data summarization.  To group a set of observations, we select a set of class intervals. There must be no overlapping between these intervals.  Too few intervals are undesirable because of the resulting loss of information. If too many intervals are used, the objective of summarization can not be met. The appropriate No. of class intervals is 6-15.
  4. 4. The frequency distribution, cont. Sturge’s rule (formula): K = 1 + 3.322 (log10 n) K = No. of class intervals. n = sample size. Note that this rule is not final, you can increase or decrease the No. of class intervals for convenience and clear presentation.
  5. 5. The frequency distribution, cont. The width (W) of class interval, in general, is equal, but sometimes this is not possible.W = R/K R = Range (difference between smallest and largest observation). For convenience, a width of 5 units or 10 units is used.
  6. 6. Example of a frequency distributiontable of 169 subjects of differentagesClass Frequency Cumulative Relative Cumulative R.interval frequency frequency Frequency10-19 4 4 0.0237 0.023720-29 66 70 0.3905 0.414230-39 47 117 0.2781 0.692340-49 36 153 0.2130 0.905350-59 12 165 0.0710 0.976360-69 4 169 0.0237 1.0000Total 169 1.0000
  7. 7. 90 80 70 60 50Success rate % 40 30 20 10 0 College Erbil Sulaimany Duhok Figure 1. Success rate by college
  8. 8. 6 5 4frequency 3 2 1 0 17.5 20 22.5 25 27.5 30 32.5 35 37.5 40 42.5 45 47.5 Age (years) The Frequency Polygon
  9. 9. 70 60 50 40frequency 30 20 10 0 10 to 19 20 to 29 30 to 39 40 to 49 50 to 59 60 to 69 Distribution of Sample by Age Age (years) Line Graph
  10. 10. Males, 150, 33%Females, 300, 67% Figure 1. Distribution of sample by sex

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