Common Measures of Central Tendancy
Your Ad Here

Common Measures of Central Tendancy

Biostatistics

Community Dentistry

[Soben Peter 4th ed 381-82/ 5th ed 603-04]
 
Arithmetic mean, Median, Mode are common measures of central tendency.
 
a) Arithmetic Mean (x̄)
  • It is simplest measure of central tendency.
  • It is obtained by summing up all the observations divided by the number of observations.
  • It is not an appropriate measure for very skewed distributions as it is very sensitive to extreme scores.
 

b) Median (Md)

  • It is the simplest division of a set of measurements into two halves - the upper and lower half, The point on the scale that divides the group in this way is median.
  • Median is insensitive to small numbers of extreme scores in a distribution; therefore it is a very useful measure of central tendency for the highly skewed distributions,
  • When the distribution has odd number of elements, middle value is median, When the distribution has even number of elements, the average of two middle scores is Median.
 
c) Mode
  • It is the most frequently occurring value in a set of observations,
  • If only two scores occur with greatest frequency, the distribution is bimodal.
  • If more than two scores occur with greatest frequency, the distribution is multimodal.
Your Ad Here