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# Ocr mei statistics 1 exam thread (24/05/13) watch

1. Is this for GCSE or A-Level 0.0
2. How long are you supposed to spend on each section?
3. (Original post by 0utdoorz)
How long are you supposed to spend on each section?

Personally I spend about half an hour on each then have plenty of time left for checking.
4. (Original post by socialgain)
Is this for GCSE or A-Level 0.0
AS level
5. (Original post by jo7777)
AS level
Oh good I'm taking GCSE stats next month and I got scared when I looked at a exam paper posted in this thread lol
6. Does anyone know if you will still get all the marks in a 5-6 marker on mean and standard deviation if you use the calculator programme with no working out shown? It's so much easier and quicker...I can't be bothered with the formulas.
7. (Original post by Saif95)
Does anyone know if you will still get all the marks in a 5-6 marker on mean and standard deviation if you use the calculator programme with no working out shown? It's so much easier and quicker...I can't be bothered with the formulas.
It's best to show a little bit of working just in case. What I do is, I work it all out on the calculator, but I write down some preliminary working with the values given (eg, mean = sum of x/n) just in case. Because if you wrote down the mean and SD without working, but accidentally typed a wrong number into your calculator, you'd get no marks.
8. When you do the critical region method on a hypothesis test are you looking for values above and below the significance level and how would you conclude ?

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9. (Original post by Imog)
It's best to show a little bit of working just in case. What I do is, I work it all out on the calculator, but I write down some preliminary working with the values given (eg, mean = sum of x/n) just in case. Because if you wrote down the mean and SD without working, but accidentally typed a wrong number into your calculator, you'd get no marks.
But if you were to get the right answer without typing a wrong number and you write from calculator= (answer) would you get all the marks or just one mark?
10. (Original post by Saif95)
But if you were to get the right answer without typing a wrong number and you write from calculator= (answer) would you get all the marks or just one mark?
IMO, i don't think they would give it to you!
Because they would give you the accuracy mark for getting the right answer, but how could you get the method marks if you haven't used a method?
11. ITS TOMORROW!
I think i'm going to cry :'(
12. (Original post by krishkmistry)
When you do the critical region method on a hypothesis test are you looking for values above and below the significance level and how would you conclude ?
The critical region is the region in which you accept the null hypothesis.
For example the critical region could be X < 2. To conclude you state whether x (number of something happening e.g heads on a coin) is within the critical region or not, and whether the null or alternative hypothesis should be accepted.

E.g

critical region is X < 2
in trial x = 1, x is within the critical region
Reject Null hypothesis, conclude there is enough evidence to suggest... (the coin is biased etc)
13. (Original post by Kalapatato)
The critical region is the region in which you accept the null hypothesis.
For example the critical region could be X > 2. To conclude you state whether x (number of something happening e.g heads on a coin) is within the critical region or not, and whether the null or alternative hypothesis should be accepted.

E.g

critical region is X > 2
in trial x = 1, x is not within critical region
Reject Null hypothesis, conclude there is enough evidence to suggest... (the coin is biased etc)
I thought it was the other way around. I thought the critical region is the region where you reject the null hypothesis.
14. (Original post by 0utdoorz)
What about the interquartile range, variance and standard deviation? What does the skewness affect?
Interquartile range is NOT AFFECTED by outliers, as it's only the middle data that is used (25% - 75%), so It's a useful measure of spread.

Variance & Standard deviation are like the mean, they use ALL VALUE DATAs, so are affected by outliers, but not as much as the Mid range_

Skewness can affect all of them? But If it's positive skew, the Mean will be lower (If the values are in ascending order (1,1,2,4,4,8,9) & higher if the values are in decending order, i.e., 10,9,9,8,7,5,2,1). So the skew will affect the mean, It'll also affect the median, as the centre value is going to be closer to whatever skew (I.e, with values; 1,1,1,2,3,3,5,8,9). The median is 3, and it's positively skewed, it was affected, I think. Not to sure on this).

Mainly ignore range & mid range. As the data could be (1,1,1,1,1,2,2,3,4,5,20) A box & whiskers diagram would have really long whiskers to the right, showing that its negative skew, but thats just an outlier, so Mainly look at the IQR & median for skew).
I thought it was the other way around. I thought the critical region is the region where you reject the null hypothesis.
Sorry about the confusion, this is the right way around
16. (Original post by Kalapatato)
Sorry about the confusion, this is the right way around
No worries.
17. You know for Permutations and Combinations? Which one should be done in order and which one you can choose?
18. (Original post by Kalapatato)
Sorry about the confusion, this is the right way around
I'm confused, if it's in the critical region, you reject the null hypothesis?
19. (Original post by sasunerd)
I'm confused, if it's in the critical region, you reject the null hypothesis?
If it's within the critical reigion you accept the null hypothesis
20. Could someone explain question 6 part ii on the jan 2010 paper? I can do the first part but don't know why the second part is (20^3)-20 which is what the markscheme says.

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