Measures of Location – AS Maths Revision – Statistics (S1)

Intro

  • Measures of location are a form of numerical representation of data
  • They’re basically just averages
  • You’ve got the mean, the median and the mode
  • I’m sure you know what they are, if you’ve made it as far as A-Level Maths
  • I’ll cover finding them from charts / diagrams in a different post

The Mode

  • The mode is pretty easy to calculate
  • Calculate? You just count to find out which one occurs the most!
  • There could be no mode, or there could be several modes
  • It’s not affected by anomalously extreme values
  • It works for both qualitative and quantitative data
  • Unfortunately, it’s got no useful mathematical purposes

The Median

  • The median is also not affected by extreme values
  • It’s still not as useful as the mean
  • It’s easy to find from raw data – you just look for the middle one
  • (If there’s an odd number of numbers, there will be an obvious middle number. If it’s an even number of numbers, you’ll have to go half way between the two middle numbers – unless the two middle numbers are identical, which would be nice)
  • Finding it from group data is trickier, though…

The Mean

  • It uses all the values in the data set
  • Unfortunately, that means extreme values can distort it
  • Its uses include being part of the standard deviation and standardizing normal distributions…
  • Add all the data and divide by the number of items of data – you know the drill
  • The formula for the mean can be written as pronounced “x bar equals sigma x over n”, where x bar is the letter x with a horizontal line over it, sigma is that Greek letter that looks a bit like a capital E, and means “the sum of”, and n is the letter n, representing the number of items of data in the data set.
    I’d draw it for you, but I don’t have a graphics tablet on me…
Advertisements

About Matt

I like writing, filmmaking, programming and gaming, and prefer creating media to consuming it. On the topic of consumption, I'm also a big fan of eating.
This entry was posted in AS Maths Revision and tagged , , , , , , , , , , , . Bookmark the permalink.

Enter comment:

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s