By Suha Tayyab
BIOSTATISTICS- MEASURES OF CENTRAL TENDENCY AND RANGE
Biostatistics are statistical processes and methods applied to analyze and interpret data especially related to medicine.
One of the most common and easiest functions applied to data is the measure of central tendency. It identifies a central position in a data set. Measures of central tendency include:
Mean
Median
Mode
For better understanding, each term will be explained using a sample question.
A group of 6 students appeared in the exam and scored the following marks. Calculate mean, median, mode. Data set (20,20,22,23,28,31)
Mean
Is the average of a data set. The mean is equal to the sum of all values divided by the number of values in a data set.
(Sum of all values )/ total number
(20+20+22+23+28+31)/6 = 24
Median
Is the middle value of a data set when arranged in ascending or descending order.
If the number of values in a data set is odd, the middle value of the arranged list will be the median.
Example 20,20,22,23,28,31,32 (number of values= 7)
Median= 23
If the number of values in a data set is even, the two middle values will be added and divided by 2. The answer will be the median.
20,20,22,23,28,31 (number of values= 6)
(Sum of middle two values)/2
22+23/2= 22.5
Mode
Is the most repeated number in a data set.
20,20,22,23,28,31
MODE: 20
Another function applied to data is the Range. It explains the spread of data in a data set.
The range is the difference between the highest and the lowest values in a data set.
Example: A group of 6 students appeared in the exam and scored the following marks. Calculate range
(20,20,22,23,28,31)
Highest value: 31
Lowest value:20
31-20= 11
In practice, a large volume of data is collected from experiments or researches, and to analyze and apply these functions, applications like Microsoft Excel, SPSS are used.
We will work with sample data in excel and calculate measures of central tendency.
Before we begin, we will talk about what Microsoft Excel is.
Microsoft Excel is spreadsheet software used to organize data in rows and columns. It is used to perform various mathematical and statistical functions to the data.
To calculate the mean of heights in the example below, use the function
=AVERAGE(cells containing data of interest)
Click on the first cell drag the cursor to the last cell with data of interest to be selected. Press enter
To calculate the median of heights in the example below, use the function
=MEDIAN(cells containing data of interest)
Click on the first cell drag the cursor to the last cell with data of interest to be selected. Press enter
To calculate the mode of heights in the example below, use the function
=MODE(cells containing data of interest)
Click on the first cell drag the cursor to the last cell with data of interest to be selected. Press enter
To calculate the range of heights in the example below, use the function
=MIN(cells containing data of interest)
=MAX( cells containing data of interest)
Subtract the min and max values calculated in cells using cell names
That was about it! These functions make life that much easier!