Facebook Twitter

Biology first year statistics mean

  1. Read the task in Box 1.
  2. Download each of the pdfs and read them. Keep these open so you can refer to them as you watch the video.
  3. Watch the video.

Step 1

The Task

Understanding statistics and experimental design is vital for life sciences and many students dread the idea of it because they lack a robust mathematics background.
I set these two questions as I wanted my students to be able to explain what ‘mean’, ‘median’ and ‘range’ mean .

Question one
‘Mean’ and ‘median’ are key concepts in statistics, but students often confuse them. I set this question because I wanted to find out how well students could differentiate between them. I wanted students to be very precise in their definitions, something along the lines of, ‘The mean is equal to the sum of all the values in the data set divided by the number of values in the data set. It is the average of the dataset and it is affected by sample size as well as outliers.’ For the ‘median’ I expected, ‘The median is the middle value for a set of data that has been arranged from low to highest value. The median is less affected by sample size and outliers.’

Question 2
I also wanted the students to think about the meaning of ‘the range’ and crucially here, I wanted them to understand that the range shows the dispersal of the data. So I expected them to write something like, ‘The range is the difference between the smallest and the largest observed value. The range is a measure of the spread or the dispersion of the observed values.’

Step 2


Text 1

Q1. To show the average of the data. To give an idea of outliers.

Q2. It gives a measure of dispersion of the data.

Text 2

Q1. We use the mean value as it gives the overall average of a set of data, and the median value gives a representation of the middle value for a data set which fluctuates.

Q2. The difference between the highest value in a data set and the lowest value in a data set. It is the simplest measure of spread.

Text 3

Q1. We use mean as it gives us an average value of a number of values. The average value best represents the whole data set. The median is the middle value in a data set where there is an array of higher and lower values. The median gives a better representation used to test hypothesis to analyse the collected data.

Q2. The range gives you the difference between the highest and lowest values in a data set. The range shows how spread the data is. 

Step 3

Step 4

Download the transcript for this video.

Creative Commons Licence