3 More about data
Averages are used frequently in reports and in the media to summarise data. When you come across an average in this way, it’s worth asking yourself some questions before drawing any conclusions.
- Do you know what kind of average was used?
- How many values were used to calculate the average?
- How were the data collected?
Then you’ll be prepared to consider the data, and the type of average used, in a critical manner. The more data that has been used to calculate the average, the more likely it is to be a reliable result.
When averages are calculated, this may be based upon a sample of the total data available rather than all the data, particularly when dealing with large populations.
For example, if you wanted to know the average height of women in a country, it would be impractical to measure and record this value for all women – so a sample of the population would be taken. The more measurements you had from across the whole country, the better idea you would get of an average value for the whole population. As well as this, the more data that you have, the less influence extremes can have on the average if the mean is used, which it generally is.
Similarly, if the data were only collected from schools for example, that also would not be a true representation of the average height. So, how the data were collected is also important.
So, next time you see or hear an average value quoted, see if you can find out what lies behind it!
Now you have looked at a few ways to analyse data, let’s move on to how to present data using tables.