Beege said:
* What Is A Decile? e.g. In A Graph
* Finding the 1st 2nd and 3rd quartiles e.g. In this set of data - 9, 9, 10, 11, 12, 12, 13
* The Different types of data e.g. Categorical etc.
Would be great help thanks
When you have a set of data, you can split all the scores up into small groups.
You can split the data up into 4 equal groups - quartiles
You can split the data up into 10 equal groups - deciles
You can split the data up into 100 equal groups - percentiles.
You've probably heard about exam results talked about in things like the "top percentile" or the 91-100% percentile (which is really a decile).
For types of data, you can have either NUMERICAL (cars per household, height of students) or CATEGORICAL (favourite colour, brand of toothpaste).
For numerical data, you can also split this into DISCRETE (number of cars, number of pets) or CONTINUOUS data (height, weight, temperature).
A good trick to see if data is discrete is to see if the question says "number of ..."
For your set of data: 9, 9, 10, 11, 12, 12, 13
The minimum is 9 and the maximum is 13. (These are sometimes called Q0 and Q4.)
Now find the middle score (median). It's 11. (Which is Q2.)
Now on either side of 11, there are three scores, so ignoring the median you've created 2 equal groups. One is 9, 9, 10 and the other is 12, 12, 13.
Now find the median of each of these groups. One is 9, which is Q1 and the other is 12, which is Q3.
So:
Minimum = 9
Q1 = 9
Median = 11
Q3 = 12
Maximum = 13
which is also called the five number summary.
Now you can draw a box-and whisker plot.