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AQA Biology Empa 2013 help needed with stats! watch

1. Hey I have my biology EMPA soon and I am really struggling with standard error I get the other 2 its just standard error I just dont understand how you would reject or accept the null hypothesis....any help would be really appreciated!
2. Hey I haven't done it yet, mine is next Monday!

You're ususally given the formula to calculate Standard Error in the exam, SE= SD/ (square root of n) you multiply this by 2 then add it to the mean once and take away once

this gives you a point above and below the mean. You will have to do it for two sets of data so once you're done you can see whether there's overlap (you can see this by comparing the lower value for one with the higher value of the other. Or you can plot them both on a graph and see if the standard error bars overlap)

If there's an overlap you accept the null hypothesis as there's no significant difference between the two means at a probability of 0.95. Any differences are due to chance.

However, if they don't overlap, then there's a significant difference between the means, we reject the null hypothesis.

I know that sounds a bit waffly but hopefully it makes sense
3. Thank you so much that did help! if there was no overlap then I would reject the null hypothesis and say that there is a probability of less than 5% that the difference is due to chance?
4. Anyone got any advice on this year's Empa? (AQA)
5. Can someone please give me a list of topics to revise for task 3
Thanks, much appreciated

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6. How have the empa's gone? what did it include? im abit puzzled on the table, thanks!
7. Hey! What is the Empa on? What are the 2 tasks? I'm really panicking and I've never done EMPAs or ISAs! So it's stressful! Please help!
8. Can someone explain to me the times in which you should use both of these;
P>0.05
P<0.05

and which means due to chance , not due to chance

Thanks very much
9. P<0.05 There a less than 5 percent probability that the results are due to chance. Results ARE significantly different. Therefore you REJECTS the null hypothesis

P>0.05 There more than 5 percent probability that the results are due to chance. Results are NOT significantly different. Therefore you ACCEPT the null hypothesis

Note: the greedy crocodile will face in the direction of the largest item
ie 5>4 means five is greater than four
So P>0.05 means probability of chance is greater than five percent

I hope this makes sense!
Posted from TSR Mobile
10. (Original post by Ren_9)
P<0.05 There a less than 5 percent probability that the results are due to chance. Results ARE significantly different. Therefore you REJECTS the null hypothesis

P>0.05 There more than 5 percent probability that the results are due to chance. Results are NOT significantly different. Therefore you ACCEPT the null hypothesis

Note: the greedy crocodile will face in the direction of the largest item
ie 5>4 means five is greater than four
So P>0.05 means probability of chance is greater than five percent

I hope this makes sense!
Posted from TSR Mobile
Thanks
11. Anyone able to tell me about the chance and probabilty and the null hypothesis with chi -squared and spearmens rank, and how to calculate chi-squared. Thanks ( will give +ve)

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Updated: April 17, 2013
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