# 18/05/10 Edexcel Bio 6(6BI08) watch

1. (Original post by avq8)
thank you so much for all the information can i have 1 last question??
for the t-test when we have to explain the conclusion and the significance level is 0.05
do we say the significance level is 5%
OR
do we say tht the confidence level is 95%
??? i dont knw which 1 to use because i have different markschemes with either asnwers
We say Confidence level is 95% and significance level is 0.05(probability)
2. What is the number of degrees of freedom in the experiment?
3. (Original post by samydude)
We say Confidence level is 95% and significance level is 0.05(probability)
0.05 probability means 5% !
4. (Original post by shuvo_roy)
What is the number of degrees of freedom in the experiment?
PANIC ATTACK

No. of degrees is n-1, where n is the number of Categories.

You need it to find you critical value.
5. (Original post by samydude)
PANIC ATTACK

No. of degrees is n-1, where n is the number of Categories.

You need it to find you critical value.
What is the no. of degrees of freedom in the experiment of chi-squared?
6. n=4
therefore, n-1=4-1 = 3.
3 is the degrees of freedom.
7. (Original post by samydude)
n=4
therefore, n-1=4-1 = 3.
3 is the degrees of freedom.
Thanks.....i got it!
8. You do realise that we probably don't have to find the number of degrees of freedom right?

I'd like to note:
For Mann Whitney U we use the SMALLER value of U to make conclusions. And, if the calculated value is less than critical value then we reject null hypothesis. If it is bigger we actually ACCEPT null hypothesis.

For Wilcoxon, it's the same.

Did anyone study regression analysis?
9. hi all just going through some last minute revision and i was wondering if there's anything in particular we have to study for like a checklist?

core practicals
statistics tests and when to use them

anything else?
10. (Original post by orangeism)
hi all just going through some last minute revision and i was wondering if there's anything in particular we have to study for like a checklist?

core practicals
statistics tests and when to use them

anything else?
Sampling techniques, limitations, apparatus, analysis, graphical formats and safety.
11. ppl in the t-test question in the sample the mark scheme says "at the 95% confidence level" and the past papers say 5% ... which one shall we follow?
12. I guess we can't keep off the leeches away. All they want to do here is come and give orders and don't want to help in any way.

GUYS, ATTENTION:

In ALL PAST PAPERS I worked, the markscheme has 5% confidence level. The sample is only place where I see 95%...
13. (Original post by Doughboy)
I guess we can't keep off the leeches away. All they want to do here is come and give orders and don't want to help in any way.

GUYS, ATTENTION:

In ALL PAST PAPERS I worked, the markscheme has 5% confidence level. The sample is only place where I see 95%...
I assume you're talking about the 6106/02 (W2) when you say 'past papers'. I reckon we should follow the sample (specimen) i.e 95%
14. i guess so two ama follow the sample
15. Lol. Edexcel samples have been known to have errors.

Quote from all papers I have done:

*1. calculated value (3.62) is greater than the critical value
at 5% level 2.10) ;
*At the 5% significant level / 0.05 probability level ;
*1. calculated value (0.333) is below the critical
value (0.648) at the 5% confidence level ;
*1. calculated value (3.81) is greater than the critical
value at 5% level (1.98) ;
KATZ_Meighan says:
*yea
Live It Up! says:
*there is a significant correlation between numbers of dogwhelks and
numbers of barnacles ;
at the 5% confidence level (not simply p=0.05) ;
*At the 5% confidence level / eq ;
*the safest one so far is 5% confiedence
*At the 5% confidence limit / greater than 2.10 ;
*Calculated (correlation) coefficient is greater than the critical value ;
At the 5% value = 0.567 ;

*At the 5% confidence level / greater than 2.02;
* At the 5% value; [not just P = 0.05]
The safest thing to say is 5% confidence level or 5% value. I'll look it up more and come back with an answer.
16. (Original post by Doughboy)
Lol. Edexcel samples have been known to have errors.

Quote from all papers I have done:

The safest thing to say is 5% confidence level or 5% value. I'll look it up more and come back with an answer.
No harm in mentioning both. Significance and Confidence
17. (Original post by Doughboy)
I guess we can't keep off the leeches away. All they want to do here is come and give orders and don't want to help in any way.

GUYS, ATTENTION:

In ALL PAST PAPERS I worked, the markscheme has 5% confidence level. The sample is only place where I see 95%...
This is really sth to take into account! But years of mark scheme, all saying 5% cant be a mistake.....and 5% and 95% confidence level is not same !!
18. Well, they usually mention whether it's significance or confidence in the question anyway, right?
19. I'm just gonna say that blah blah blah... at the 5% significance level (being 95% confident).
20. (Original post by LetoKynes)
Well, they usually mention whether it's significance or confidence in the question anyway, right?
Please explain to me the difference between the two

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