Standard Deviation Statistics Coursework Help

 
  1. I'm in Year 10 and I'm going to start my statistics coursework next week which is very soon, however I honestly have no idea what we're doing. I understand already that our theme is holidays and we will be given a set of secondary data. But I do not know further than this. I am desperate to get an A* in my coursework and I need some help! We have gone over some of the basics (that are not A-A* grades) like qualitative, quantitative, continuous, discrete, data logging machines etc.

    I want to know what the structure is; how long I have to complete it; what we are actually writing; what key facts I need to know

    Thanks

  2. So I got an A in my statistics coursework last year( 31/40) and I was 2 marks of an A*. I don't actually know of anyone who has got an A* in the stats coursework- in real life and the student room- so it's very rare.( Statistically for AQA this year more people got an A* in maths than for statistics)

    For me the coursework lasted for the entirety for the school day and I got one day to do it- your school might be different. You should be giving sort of writing frame( I was)-
    Firstly are you on AQA? If not then I won't be able to help as much- but one huge tip is to read the examiners report- it tells you exactly what you need to include and where students have gone wrong- it will help you achieve the top grades.

    To actually get A* grades you have to use A/A* techniques and interpret them and how they are relevant to your given hypothesis. Use histograms, grouped frequency tables, standard deviation, mean, median, mode, intq, boxplots etc
    (Original post by Pandora___)
    I'm in Year 10 and I'm going to start my statistics coursework next week which is very soon, however I honestly have no idea what we're doing. I understand already that our theme is holidays and we will be given a set of secondary data. But I do not know further than this. I am desperate to get an A* in my coursework and I need some help! We have gone over some of the basics (that are not A-A* grades) like qualitative, quantitative, continuous, discrete, data logging machines etc.

    I want to know what the structure is; how long I have to complete it; what we are actually writing; what key facts I need to know

    Thanks

    Last edited by gapyear2018; 11-09-2015 at 23:02.

  3. As the previous post stated, it depends on your exam board.
    Idk about edexcel but for AQA your teacher can help a little and you can take your revision guide and whatever you need with you.
    (Original post by Pandora___)
    I'm in Year 10 and I'm going to start my statistics coursework next week which is very soon, however I honestly have no idea what we're doing. I understand already that our theme is holidays and we will be given a set of secondary data. But I do not know further than this. I am desperate to get an A* in my coursework and I need some help! We have gone over some of the basics (that are not A-A* grades) like qualitative, quantitative, continuous, discrete, data logging machines etc.

    I want to know what the structure is; how long I have to complete it; what we are actually writing; what key facts I need to know

    Thanks

The standard deviation measures the spread of the data about the mean value. It is useful in comparing sets of data which may have the same mean but a different range. For example, the mean of the following two is the same: 15, 15, 15, 14, 16 and 2, 7, 14, 22, 30. However, the second is clearly more spread out. If a set has a low standard deviation, the values are not spread out too much.

Just like when working out the mean, the method is different if the data is given to you in groups.

This video shows you how to calculate the Standard Deviation

Non-Grouped Data

Non-grouped data is just a list of values. The standard deviation is given by the formula:

s means 'standard deviation'.
S means 'the sum of'.
means 'the mean'

Example

Find the standard deviation of 4, 9, 11, 12, 17, 5, 8, 12, 14
First work out the mean: 10.222
Now, subtract the mean individually from each of the numbers given and square the result. This is equivalent to the (x - )² step. x refers to the values given in the question.

x 4 9 11 12 17 5 8 12 14
(x - )2 38.7 1.49 0.60 3.16 45.9 27.3 4.94 3.16 14.3

Now add up these results (this is the 'sigma' in the formula): 139.55
Divide by n. n is the number of values, so in this case is 9. This gives us: 15.51
And finally, square root this: 3.94

The standard deviation can usually be calculated much more easily with a calculator and this may be acceptable in some exams. On my calculator, you go into the standard deviation mode (mode '.'). Then type in the first value, press 'data', type in the second value, press 'data'. Do this until you have typed in all the values, then press the standard deviation button (it will probably have a lower case sigma on it). Check your calculator's manual to see how to calculate it on yours.

NB: If you have a set of numbers (e.g. 1, 5, 2, 7, 3, 5 and 3), if each number is increased by the same amount (e.g. to 3, 7, 4, 9, 5, 7 and 5), the standard deviation will be the same and the mean will have increased by the amount each of the numbers were increased by (2 in this case). This is because the standard deviation measures the spread of the data. Increasing each of the numbers by 2 does not make the numbers any more spread out, it just shifts them all along.

Grouped Data

When dealing with grouped data, such as the following:

xf
4 9
5 14
6 22
7 11
8 17

the formula for standard deviation becomes:

Try working out the standard deviation of the above data. You should get an answer of 1.32 .

You may be given the data in the form of groups, such as:

NumberFrequency
3.5 - 4.5 9
4.5 - 5.5 14
5.5 - 6.5 22
6.5 - 7.5 11
7.5 - 8.5 17

In such a circumstance, x is the midpoint of groups.

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