S2 Edexcel Tuesday 17th January SOLUTIONS IN FIRST POST

I won't be able to post it until the next day. Probably some time in the early afternoon.
You can all have fun arguing about it until then!!

Do you happen to have the mark schemes to the old T1/T2 (statistics) papers for Edexcel? I have some papers from 1996, but no mark scheme, unfortunately...

Thanks for everything.

Reply 61

Gibbo81

OP

1

Original post by snow leopard

Gibbo could you please clarify these comments on an S2 MS? When converting from a PDF that has two functions to a CDF, the MS says:

Spoiler

What do they 'condone' exactly... I thought the signs in the CDF interval didn't matter. Also, what doesn't 'need to match up'?

The don't match up comment means that you can have <= on one interval followed by a >= on the next one (clearly they can't both be =).

Strictly it does matter in the CDF for example if your pdf has 1<x<2 the first region on your cdf should be x<=1 followed by 1<x<2 followed by x>=2. But they're saying you can put < or <= it doesn;t matter.

Reply 62

Gibbo81

OP

1

Original post by Zhy

Do you happen to have the mark schemes to the old T1/T2 (statistics) papers for Edexcel? I have some papers from 1996, but no mark scheme, unfortunately...

Thanks for everything.

No I'm afraid not. I was a bit too young for A Level Stats in 1996!!

Reply 63

snow leopard

1

Original post by Gibbo81

The don't match up comment means that you can have <= on one interval followed by a >= on the next one (clearly they can't both be =).

Strictly it does matter in the CDF for example if your pdf has 1<x<2 the first region on your cdf should be x<=1 followed by 1<x<2 followed by x>=2. But they're saying you can put < or <= it doesn;t matter.

Well explained thanks :smile:

Reply 64

safmaster

7

Original post by Gibbo81

...

Hey Gibbo, do you have to always define the variable you are calculating (i.e. writing "let X be a random variable that..."), or can you get away with not doing so?

Reply 65

Zhy

17

Original post by safmaster

Hey Gibbo, do you have to always define the variable you are calculating (i.e. writing "let X be a random variable that..."), or can you get away with not doing so?

Since S2 is usually finished before the allotted time by a lot of candidates then I'd say do it. You will have the time to write that out.

Reply 66

Rahul.S

14

Original post by safmaster

Hey Gibbo, do you have to always define the variable you are calculating (i.e. writing "let X be a random variable that..."), or can you get away with not doing so?

like in binomial if x--random variable that represents no. of sixes for instance?..........no mark scheme rewards the idea of a random variable except for definitions.....

p.s.: did you get an offer? :tongue:

Reply 67

safmaster

7

Original post by Rahul.S

like in binomial if x--random variable that represents no. of sixes for instance?..........no mark scheme rewards the idea of a random variable except for definitions.....

p.s.: did you get an offer? :tongue:

Hey mate, yeah I got an offer; well done on your offer!

Yeah, that's what I meant. I hardly do that when I'm doing past papers, but in the exam we may as well do it just to be sure. I normally finish in about half an hour anyway so I'll have plenty of spare time.

Are you doing S2 aswell?

Reply 68

Rahul.S

14

Original post by safmaster

Hey mate, yeah I got an offer; well done on your offer!

Yeah, that's what I meant. I hardly do that when I'm doing past papers, but in the exam we may as well do it just to be sure. I normally finish in about half an hour anyway so I'll have plenty of spare time.

Are you doing S2 aswell?

yh ive done 3 papers so far and got 74 73 75 lol....planning to do 10 tonight....it takes me about 30-40 mins as well :tongue:

I think people can mention the random variable thing but I doubt it will warrant marks unless in definitions.....but yh with the extra time I'm sure its a good thing to do and you will be checking your answers whilst doing that :wink:

guessing 1,1?

Reply 69

safmaster

7

Original post by Rahul.S

yh ive done 3 papers so far and got 74 73 75 lol....planning to do 10 tonight....it takes me about 30-40 mins as well :tongue:

I think people can mention the random variable thing but I doubt it will warrant marks unless in definitions.....but yh with the extra time I'm sure its a good thing to do and you will be checking your answers whilst doing that :wink:

guessing 1,1?

Yeah: 1, 1. Doing several exams in Jan so I can dedicate myself to mastering STEP day and night from Feb to June... quite excited by the challenge. :tongue:

Reply 70

Rahul.S

14

Original post by safmaster

Yeah: 1, 1. Doing several exams in Jan so I can dedicate myself to mastering STEP day and night from Feb to June... quite excited by the challenge. :tongue:

yh same

I reckon 4 months should be enough time as long spent wisely :smile:

Reply 71

YingYang

anyone got any revision notes to share? some measly rep in it if you do :smile:

Reply 72

Gibbo81

OP

1

Original post by Rahul.S

yh ive done 3 papers so far and got 74 73 75 lol....planning to do 10 tonight....it takes me about 30-40 mins as well :tongue:

I think people can mention the random variable thing but I doubt it will warrant marks unless in definitions.....but yh with the extra time I'm sure its a good thing to do and you will be checking your answers whilst doing that :wink:

guessing 1,1?

Original post by safmaster

Hey mate, yeah I got an offer; well done on your offer!

Yeah, that's what I meant. I hardly do that when I'm doing past papers, but in the exam we may as well do it just to be sure. I normally finish in about half an hour anyway so I'll have plenty of spare time.

Are you doing S2 aswell?

Original post by safmaster

Hey Gibbo, do you have to always define the variable you are calculating (i.e. writing "let X be a random variable that...&quot :wink:

, or can you get away with not doing so?

Nah you don't need to define the rv unless it asks you to. I do it in my model solutions so that it is clearer.

At the end of the day you don't need to include it but it is good practice to do so and it doesn't hurt!

Reply 73

Zhy

17

Original post by YingYang

anyone got any revision notes to share? some measly rep in it if you do :smile:

My definitions:

Sampling Unit - An individual member or element in a population or sampling frame.

Population - A complete collection of all items or individuals.

Statistic - A random variable that is a function of only known observations from a population, consisting of no unknown parameters.

Census - A census is where every member of the population is investigated.

Hypothesis Test - A hypothesis test is a mathematical procedure used to examine the value of a population parameter proposed by the null hypothesis H0, compared with the alternative hypothesis H1.

Sampling Frame - A list of all the members or elements in a population.

Sampling Distribution - All possible samples are chosen from the population; the values of a statistic and its associated probabilities form what is known as a sampling distribution.

Critical Region - The range of values of a test statistic that would lead you to reject the null hypothesis (H0) in a hypothesis test. The boundary (or boundaries) of a critical region is/are called the critical value(s), denoted c1 and c2.

One-tailed test - Testing whether or not a parameter is greater (or less) than a given value.

Two-tailed test - Testing whether or not a parameter is different to a given value.

Discrete Variable - A variable that can only have certain values, usually integers.

Continuous Variable - A variable that can take any value, usually in a given range.

Statistical Model - A mathematical description with allocates a probability p to each value of a variable X reflecting the relative likelihood of that value occurring.

Significance Level - The probability of rejecting the null hypothesis (H₀) when it is true.

Population Parameter - A quantity or a statistic that is fixed for a certain population.

Sample Survey - A subset of a population is investigated and data is collected about them.

Reply 74

oHellno

12

Original post by Zhy

My definitions:
x

+rep
I love you.

Reply 75

YingYang

Original post by Zhy

My definitions:

Sampling Unit - An individual member or element in a population or sampling frame.

Population - A complete collection of all items or individuals.

Statistic - A random variable that is a function of only known observations from a population, consisting of no unknown parameters.

Census - A census is where every member of the population is investigated.

Hypothesis Test - A hypothesis test is a mathematical procedure used to examine the value of a population parameter proposed by the null hypothesis H0, compared with the alternative hypothesis H1.

Sampling Frame - A list of all the members or elements in a population.

Sampling Distribution - All possible samples are chosen from the population; the values of a statistic and its associated probabilities form what is known as a sampling distribution.

Critical Region - The range of values of a test statistic that would lead you to reject the null hypothesis (H0) in a hypothesis test. The boundary (or boundaries) of a critical region is/are called the critical value(s), denoted c1 and c2.

One-tailed test - Testing whether or not a parameter is greater (or less) than a given value.

Two-tailed test - Testing whether or not a parameter is different to a given value.

Discrete Variable - A variable that can only have certain values, usually integers.

Continuous Variable - A variable that can take any value, usually in a given range.

Statistical Model - A mathematical description with allocates a probability p to each value of a variable X reflecting the relative likelihood of that value occurring.

Significance Level - The probability of rejecting the null hypothesis (H₀) when it is true.

Population Parameter - A quantity or a statistic that is fixed for a certain population.

Sample Survey - A subset of a population is investigated and data is collected about them.

thanksss

are these mark scheme definitions?

Reply 76

Zhy

17

Original post by YingYang

thanksss

are these mark scheme definitions?

Yes, all of them except the last 3. Some of them have never appeared in S2 before, but could come up (hypothesis test, for example, appeared for the first time in Jan 08, I think). I got the others from Solomon/Delphis papers, but the majority are the official definitions from mark schemes. I've picked the ones which will most likely get you the mark as they do sometimes vary a bit each year.

Reply 77

r_t

If ever there is/was/will be an exam I am/will be/have been ready for, it's this S2 paper :smile:

Reply 78

YingYang

yeah I am more confident for this s2 paper than i was last year for s1.

but i do often make stupid mistakes, particularly when intergrating. I so easily make one mistake and i have pretty much mucked up the entire answer

argh 4 exams, I hate january.