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This presentation is about the basics of Measures of Central Tendencies.
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MEASURES OF CENTRAL
TENDENCIES
Ungrouped data
MEAN
Do you have an idea what MEAN(Statistics) is?
Mean
Is the average value of a data.
Population Mean
Is the mean of the whole population
Sample Mean
Is the mean of the part of the population
Example Problems
1) The number of faculty members in 10 different colleges are 16, 25, 40, 24, 15, 20, 50, 15, 35 and 20. Treating the data as a population, find the population mean of faculty members for the 10 colleges.
2) The following are the ages of the 9 children in a squatters area. Find the mean.Ages: 9, 8, 1, 3, 4, 5, 6, 7, 2
MEDIAN
So, what is median? Can you give some ideas about it?
MedianIs the value found at the middle when the data are arranged in an array form from the highest to the lowest or from the lowest to the highest.
x987654321
5
Example
The MEDIAN
1)
x9876543211
2)
4
5
The MEDIAN
MODE
Mode
Is the value which occurs most often or with greatest frequency.
x1099765321
9
Example
The MODE1) 9
x18181717171616161515
2)
16
17
The MODE
1717
16
16
17 and 16
grouped data
What is a grouped data?
MEAN
In finding the mean in a grouped data, we use this formula:
Example
A frequency distribution of the scores in English of 34 Education students.
x f m fm35 – 39 330 – 34 525 – 29 820 – 24 1015 – 19 410 – 14 2
5 - 9 2
x f m fm35 – 39 3 37 11130 – 34 5 32 16025 – 29 8 27 21620 – 24 10 22 22015 – 19 4 17 6810 – 14 2 12 24
5 - 9 2 7 14
MEDIAN
Where: __– median___– half sumF – cumulative
frequencyf – frequencyi – interval
x f F35 – 39 330 – 34 525 – 29 820 – 24 1015 – 19 410 – 14 2
5 - 9 2
x f F35 – 39 3 3430 – 34 5 3125 – 29 8 2620 – 24 10 1815 – 19 4 810 – 14 2 4
5 - 9 2 2
MODE
Where:___ - mode__ - median__ - mean
Mean = 23.91Median = 24Find the mode using the formula given.