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rae
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#41
Report 16 years ago
#41
(Original post by crana)
Cheers I think I'm alright without that paragraph but thanks for the offer! I agree, I think it's polar too - agree about the ethanol, I think we have used it in chemistry mixed with water to help not-very-polar things dissolve. I was kind of trying to make the point that it being soluble in alcohol didn't make it non-polar, but I guess I didn't put it across well!

good luck with your coursework
rosie

ps. Im from nottingham too
we were talking about the social or is that another rosie?
aside from a bit of tickling up, ive finished it!
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crana
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#42
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#42
(Original post by rae)
we were talking about the social or is that another rosie?
aside from a bit of tickling up, ive finished it!
no I think that must be another rosie.
mine is nearly there, but I have a vague memory of our teacher telling us we needed to include some kind of stats tests, so im trying to get those in!

rosie
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rae
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#43
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#43
(Original post by crana)
no I think that must be another rosie.
mine is nearly there, but I have a vague memory of our teacher telling us we needed to include some kind of stats tests, so im trying to get those in!

rosie
i saw your post on T-tests but wasnt sure enough to reply to that particular thread! i think its suitable so long as your actual range is 7-30. i didnt see how you could use the chi squared.
im curious about what the practical could be; theyre usually connected (to the plan)
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crana
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#44
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#44
(Original post by rae)
i saw your post on T-tests but wasnt sure enough to reply to that particular thread! i think its suitable so long as your actual range is 7-30. i didnt see how you could use the chi squared.
im curious about what the practical could be; theyre usually connected (to the plan)
hi
i asked a friend who does Environmental Biology as his optional module (we do app. of genetics) and he said in th E.biology book it says you need 6 or more in each "set". So 6 it is.

I thought about using chi-squared for germination (I'm doing % of seeds germinated after 2 days - well, im using 100 seeds at a time, so it's really just count the seeds) but I'm not sure - I mean it's counted, not measured, which is discontinuous.. but as a %, %s should be continuous. I think.

So yeah, and use my expected values as the germination rates from the control.

D'you think that's not OK because the %s are continuous..? or are they discontinuous? have to admit, I'm not really sure!

last year (AS) the plan was not incredibly connected to the rest of the practical, iirc, the only "theme" in evidence was "biological molecules"!

Rosie
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crana
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#45
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#45
(Original post by crana)
hi
i asked a friend who does Environmental Biology as his optional module (we do app. of genetics) and he said in th E.biology book it says you need 6 or more in each "set". So 6 it is.

I thought about using chi-squared for germination (I'm doing % of seeds germinated after 2 days - well, im using 100 seeds at a time, so it's really just count the seeds) but I'm not sure - I mean it's counted, not measured, which is discontinuous.. but as a %, %s should be continuous. I think.

So yeah, and use my expected values as the germination rates from the control.

D'you think that's not OK because the %s are continuous..? or are they discontinuous? have to admit, I'm not really sure!

last year (AS) the plan was not incredibly connected to the rest of the practical, iirc, the only "theme" in evidence was "biological molecules"!

Rosie
Just been having a surf around and I think I should be ok to use chi-squared on my germination rates, as long as I use actual numbers of seeds instead of %s (they're the same thing here. but you know what i mean)

(from eBMJ: It is important to emphasise here that tests may be carried out for this purpose only on the actual numbers of occurrences, not on percentages, proportions, means of observations, or other derived statistics. )

http://bmj.bmjjournals.com/collections/statsbk/8.shtml

gotta say a lot of stats flies high above my head, so if I completely have the wrong end of the stick, someone please tell me
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rae
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#46
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#46
(Original post by crana)
hi
i asked a friend who does Environmental Biology as his optional module (we do app. of genetics) and he said in th E.biology book it says you need 6 or more in each "set". So 6 it is.

I thought about using chi-squared for germination (I'm doing % of seeds germinated after 2 days - well, im using 100 seeds at a time, so it's really just count the seeds) but I'm not sure - I mean it's counted, not measured, which is discontinuous.. but as a %, %s should be continuous. I think.

So yeah, and use my expected values as the germination rates from the control.

D'you think that's not OK because the %s are continuous..? or are they discontinuous? have to admit, I'm not really sure!

last year (AS) the plan was not incredibly connected to the rest of the practical, iirc, the only "theme" in evidence was "biological molecules"!

Rosie
hmm, youve got me thinking now! im investigating % germination after 36 hours and mean growth after 72 hours (i think, and from the start). i was going to use pure water as my control and compare the [ABA] results to this. so i assumed i would have 2 means if you like so id use the T-test.

i rejected chi squared as you dont know what to expect when you add the ABA (we do app of genetics too and chi squared seemed to be more to do with epistasis and gene control etc etc, when you think you know what you're going to get). ive also got a worksheet with a similar problem to the one we're doing which uses the T-test.

oh dear. all in a quandry!!!

ill have a think and get back to you on tuesday night; im working til then so wont have a chance to get online.

lets hope we have some revelations!!!
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crana
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#47
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#47
(Original post by rae)
hmm, youve got me thinking now! im investigating % germination after 36 hours and mean growth after 72 hours (i think, and from the start). i was going to use pure water as my control and compare the [ABA] results to this. so i assumed i would have 2 means if you like so id use the T-test.

i rejected chi squared as you dont know what to expect when you add the ABA (we do app of genetics too and chi squared seemed to be more to do with epistasis and gene control etc etc, when you think you know what you're going to get). ive also got a worksheet with a similar problem to the one we're doing which uses the T-test.
I think you do know what to expect when you add the ABA/extract, if your null hypothesis is that the ABA has no effect, then your expected values should be the number germinating just with water. we also have done chi-squared mainly in the context of genetics but you can use it for other stuff too. On the link i posted, it was about admissions to different hospital wards and social class!

But yeah, if you're using processed results, then you can't use chi-squared - so t-test is your only option. But since you have your raw results anyway.. i dont know. maybe you can use either.

rosie
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Wilsoncswai
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#48
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#48
im using 100 seeds for each concentration, then see the % germination growth, obviosuly %germination is small when concentration is high. im using 5 diff. concentration, but can someone tell me how to use T-test? chi-square is used to see if the results are random or not, i dont see the point of using chi-square, well may be im being stupid (ive only used that for genetics, so i cant link that with germination resulst)> i need to sort out how to find out germination % in teh first place.. can someone help? do i use the dry mass or something? coz if dry mass increases, then it means the seed has germinated, doesnt it?
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crana
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#49
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#49
(Original post by Wilsoncswai)
im using 100 seeds for each concentration, then see the % germination growth, obviosuly %germination is small when concentration is high. im using 5 diff. concentration, but can someone tell me how to use T-test? chi-square is used to see if the results are random or not, i dont see the point of using chi-square, well may be im being stupid (ive only used that for genetics, so i cant link that with germination resulst)> i need to sort out how to find out germination % in teh first place.. can someone help? do i use the dry mass or something? coz if dry mass increases, then it means the seed has germinated, doesnt it?
"i need to sort out how to find out germination % in teh first place.. can someone help? "

you're doing 100 seeds. Look how many germinate. That's your %. Try reading the sheet, that might help you decide how to see if they've germinated.

Rosie
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Wilsoncswai
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#50
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#50
hi rosie, no sorry my teacher has only told me the title, i had to copy the title of the board, he said he is not allow to tell me anymore, thats why i keep annoying everyone by asking so many bloody questions, you can understand how frustrated im ! can you tell me which test i should use? yes i can find out the germination % by counting, what about that T test you mentioned? is it good? and chi squared?
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crana
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#51
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#51
(Original post by Wilsoncswai)
hi rosie, no sorry my teacher has only told me the title, i had to copy the title of the board, he said he is not allow to tell me anymore, thats why i keep annoying everyone by asking so many bloody questions, you can understand how frustrated im ! can you tell me which test i should use? yes i can find out the germination % by counting, what about that T test you mentioned? is it good? and chi squared?
That's really stupid. You have to hand in the sheet with your coursework, so they will have to give it you at some point. T-test and chi-squared - you should have done these in your course already. If not.. look in some textbooks? I would ask the teacher for the sheet, how are you meant to know what to do otherwise
rosie
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acidbubble
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#52
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#52
our teachers havent given us anything to do with this year's coursework, i may only get a couple of days to do it . i know its going to be about this tomato stuff. Does anybody have a copy of the plan sheet and scanner, or know where to find it online???????

thanks
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Wilsoncswai
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#53
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#53
yes it would be grateful if someone scan the sheet and so I can actually get to understand what to do... i know i need to hand the sheet it, but my teacher just wouldnt give it to us. i just had to copy the title and things given for the experiment. i know what chi square but not t-test , i have looked up txt book but cant find anything. whats T stand for? may be its in your option module which im not doing?
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Wilsoncswai
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#54
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#54
(Original post by rae)
ive got in my notes that ABA is primarily transported in the phloem. in my plan i put that this suggests it is polar which is how i justified using water for my solvent to avoid the obvious propanone issue!!!
looked up ethanol. it said it can dissolve both polar and non polar solvents. if you need more info on that pm me and ill type the paragraph up for you
hi rae , can you type up the paragraph for me, please?? thanks! or use give me the web site so i can look up... im still confused about t test... which one is the best to use?
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rae
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#55
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#55
(Original post by Wilsoncswai)
hi rae , can you type up the paragraph for me, please?? thanks! or use give me the web site so i can look up... im still confused about t test... which one is the best to use?
Source: Chemistry in Context, 4th Edition, Hill and Holman

"The lower alcohols such as ethanol tend to be good solvents for polar and non polar solvents. This is because they contain both a highly polar -OH group and a non polar hydrocarbon portion."

That's pretty much the jist of it.

Crana, I'm T-testing.
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Wilsoncswai
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#56
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#56
[QUOTE=rae]Source: Chemistry in Context, 4th Edition, Hill and Holman

is it about t-testing? what about that book? i havent got it..

why did you say ehtanol is good solvent? isnt polar solvent water and non-polar propanone? how do you use it? just give me the methods and details, dont want to get into it again coz i didnt understand last time, and i still dont fully understand, please list the steps and methods -details thanks

what is t test??
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L2wis
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#57
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#57
Hey im doing this planning paper too! I first of all want thank people for their knowledge, it's givern me some good info to base my predictions and method on. Not to mention just make me feel a little more confident! I'm poping into my schools drop in session 2morrow, to hopefully get some plimary tests done. I'm going to measure the root growth, and dilution of the tomato extract after certain periods of time. My cover sheet is probably screwed up by now.
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L2wis
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#58
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#58
Wilsoncswai when is ur planning paper due in?
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Wilsoncswai
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#59
Report 16 years ago
#59
god i feel so unlucky compare to you guys, i havent a clue what to do, im not even given that sheet which tells you what to do... i havent even done prelimiary work- and its due in 2 weeks time! havent written a word. please tell me what to do, do scan and send me the sheet or any info if you want thankssss sso much my email is [email protected] just hope i can get this done. please can someone tell me t test
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Emma18
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#60
Report 16 years ago
#60
we're doing a completely different coursework!!! growth rates of yeast cells in different temperatures!! fun!!! is anyone else doing that one??? with spearmans rank as the stats test??
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