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A2 Biology | Post your doubts here

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ok could u plz explain a bit about null hypothesis?? evry1 here is giving diferent opinions:confused:
Null Hypothesis...it assumes that any kind of difference or significance u see in a set of data is due to chance....and this null hypothesis is rejected if the probibility comes less than 5%....
or for x^2 test...therez no signeficant difference b/w the observed and the expected ratio...
 
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Null Hypothesis...it assumes that any kind of difference or significance u see in a set of data is due to chance....and this null hypothesis is rejected if the probibility comes less than 5%....
thnx :D btw where do we get da probabilty from?? :oops:
dis 1 too plzz:)
angelgirl:) :D :D
 
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Okay guys I did a few P5's and here's a tip on all those 8 mark questions which usually ask you to design an experiment.
firstly lets break it up into six portions . Independent variable, dependent variable, controlled variables, procedure, safety and reliability.
No matter how tough the question is dont panic, They dont really expect you to have any background information. 2 marks could be easily scored by telling them to repeat thrice and that 'safety' point. score further two marks by giving two variables that need to be controlled and tell them how you would control them like temp, pH. score one procedural mark ( how you will measure the dependent variable). and score another mark on how u will vary the independent variable. ( another important thing in most questions is to give time to equilibriate). REMEBER this shouldnt be the order of ur answer!!..
 
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we repeat experiment for reliability or accuracy? and wider range of concerntrations for?

to add...
for accuracy...=> always some better apparatus...

for reliability => like if u have concentration as independent vaariable, say, take atleast 5 different concentrations....and with each ....repeat at least "three times" [yup not less than that, or u wont get the mark..] , take average, and plot..

this answer is given by user:)
 
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Usually what should we write for reliability in those big 8-10 point questions? Like, calculate for the standard deviation, standard error? Can anyone give me a sample paper which includes this plz?!
 
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wht do u mean by :in a t-test, "comparing 2 means obtained from 2 samples in a population"
wht kind of 2 samples....give me an xmple sombody>???!!
 
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Could someone please upload the mark scheme for Oct/Nov 2011, paper 53? On xtremepapers, it's saying the file is broken. Thanks. ^_^
 
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