Page 5 of 11 FirstFirst ... 34567 ... LastLast
Results 101 to 125 of 253
Like Tree69Likes

Thread: Statistics Marathon & Questions

  1. #101
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon

    I am thinking the 2nd and 4th apply

    My answers would be:

    y>=32
    1:50

    Just from using R
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  2. #102
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    Quick question regarding probability spaces:


  3. #103
    Rambling Spirit
    Join Date
    Dec 2014
    HSC
    N/A
    Gender
    Male
    Posts
    6,039
    Rep Power
    7

    Re: Statistics

    Quote Originally Posted by leehuan View Post
    Quick question regarding probability spaces:

    Greater than or equal to. Events can have 0 probability.
    leehuan likes this.

  4. #104
    Loquacious One
    Join Date
    Feb 2009
    HSC
    N/A
    Gender
    Male
    Posts
    3,704
    Rep Power
    9

    Re: Statistics

    leehuan - what would you do if InteGrand decides to take a 6 month sabbatical?
    1-on-1 Maths Tutoring(IB & HSC): Epping, Beecroft, Eastwood, Carlingford & Beyond
    IB: Maths Studies, Maths SL & Maths HL; HSC: 2U, 3U & 4U
    Highly Qualified & Highly Experienced. Estimated ATAR > 9.995
    There are IB Maths Tutors and there are IB Maths Tutors.

  5. #105
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    Quote Originally Posted by Drongoski View Post
    leehuan - what would you do if InteGrand decides to take a 6 month sabbatical?
    I don't know; InteGrand can do as he wants. But why are you asking me this?
    Last edited by leehuan; 6 Mar 2017 at 12:47 PM.

  6. #106
    Loquacious One
    Join Date
    Feb 2009
    HSC
    N/A
    Gender
    Male
    Posts
    3,704
    Rep Power
    9

    Re: Statistics

    Quote Originally Posted by leehuan View Post
    I don't know; InteGrand can do as he wants. But why are you asking me this?
    Just teasing you. And noting that InteGrand has been helping you so much.
    Last edited by Drongoski; 6 Mar 2017 at 2:00 PM.
    1-on-1 Maths Tutoring(IB & HSC): Epping, Beecroft, Eastwood, Carlingford & Beyond
    IB: Maths Studies, Maths SL & Maths HL; HSC: 2U, 3U & 4U
    Highly Qualified & Highly Experienced. Estimated ATAR > 9.995
    There are IB Maths Tutors and there are IB Maths Tutors.

  7. #107
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    Quote Originally Posted by Drongoski View Post
    Just teasing you. And noting that InteGrand has been helping you so much.
    Very true. So grateful.

  8. #108
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    I wasn't taught the hypergeometric distribution properly so can someone walk me through how to use it? Here's my question if it helps to refer to it.



    A factory produces 80 items in a batch. To test if the batch is defective, an acceptance sampling scheme is adopted: a random sample of 10 items is selected, and if 2 or more items don’t meet customer specifications, the batch is considered defective.

    If there are actually 11 defective items in the batch,

    1i) What is the probability that 2 sampled items are defective?
    ii) What is a general formula for x sampled items being defective?

  9. #109
    Loquacious One
    Join Date
    Feb 2009
    HSC
    N/A
    Gender
    Male
    Posts
    3,704
    Rep Power
    9

    Re: Statistics

    Doing this for the first time for a very very long long time. Not sure if correct.

    Last edited by Drongoski; 21 Mar 2017 at 2:25 PM.
    leehuan likes this.
    1-on-1 Maths Tutoring(IB & HSC): Epping, Beecroft, Eastwood, Carlingford & Beyond
    IB: Maths Studies, Maths SL & Maths HL; HSC: 2U, 3U & 4U
    Highly Qualified & Highly Experienced. Estimated ATAR > 9.995
    There are IB Maths Tutors and there are IB Maths Tutors.

  10. #110
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    Quote Originally Posted by Drongoski View Post
    Doing this for the first time for a very very long long time. Not sure if correct.

    I think the expressions are right.

    But I'm not sure what the parameters mean either. This question is pretty much an example but for an arbitrary scenario how would I be able to tell what the parameters (N, K, n) actually meant?

  11. #111
    Rambling Spirit
    Join Date
    Dec 2014
    HSC
    N/A
    Gender
    Male
    Posts
    6,039
    Rep Power
    7

    Re: Statistics

    Quote Originally Posted by leehuan View Post
    I think the expressions are right.

    But I'm not sure what the parameters mean either. This question is pretty much an example but for an arbitrary scenario how would I be able to tell what the parameters (N, K, n) actually meant?
    The parameters are as follows:

    • N is the total population
    • K is the number of "tagged" objects (defective objects in your example)
    • n is the size of our sample.

    The hypergeometric distribution pmf Drongoski wrote (in terms of the parameters N, K, n) then gives the probability that our sample has exactly k "tagged" (defective) objects present, under the assumption that we are sampling without replacement. This follows from basic combinatorics.
    leehuan likes this.

  12. #112
    Rambling Spirit
    Join Date
    Dec 2014
    HSC
    N/A
    Gender
    Male
    Posts
    6,039
    Rep Power
    7

    Re: Statistics

    The reason for terms like "population" and "tagged" is that one place this distribution comes up is in ecology when we tag some members of an animal population (like a fish population) and then later draw (without replacement) a random sample from the animal population and count how many are tagged. This can be used to try and estimate the total population for example (it is sometimes known as the "capture-recapture method", and you can read more about it here: https://en.wikipedia.org/wiki/Mark_and_recapture).
    leehuan likes this.

  13. #113
    Supreme Member Flop21's Avatar
    Join Date
    May 2013
    HSC
    2015
    Gender
    Female
    Posts
    2,850
    Rep Power
    5

    Re: Statistics

    Any tips for catching up on stats... like any resources you use?

    Thanks I am behind lol.
    2015 HSC: English Adv, Mathematics, Business Studies, Biology, Multimedia.

    HSC Biology Flashcards

  14. #114
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    Can't deny it. I'm also a fair bit behind.

    Been cramming a lot of the course pack tbh.

  15. #115
    Supreme Member Flop21's Avatar
    Join Date
    May 2013
    HSC
    2015
    Gender
    Female
    Posts
    2,850
    Rep Power
    5

    Re: Statistics

    Quote Originally Posted by leehuan View Post
    Can't deny it. I'm also a fair bit behind.

    Been cramming a lot of the course pack tbh.
    what course pack? the questions that are on moodle or?
    2015 HSC: English Adv, Mathematics, Business Studies, Biology, Multimedia.

    HSC Biology Flashcards

  16. #116
    Ancient Orator leehuan's Avatar
    Join Date
    May 2014
    HSC
    2015
    Gender
    Male
    Posts
    5,807
    Rep Power
    6

    Re: Statistics

    Quote Originally Posted by Flop21 View Post
    what course pack? the questions that are on moodle or?
    Course pack is just what I use to call the online 'textbook' thing. It's like what we had in first year except it's just not printed.

  17. #117
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon

    Q1. If we have a data set where the median is significantly greater than the mean, which of the following is likely to be true?

    A. The data is left skewed
    B. There has been an error in data input
    C. Categorical data is being treated as numeric data
    D. The data is right skewed
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  18. #118
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon



    Based on those diagrams, the answer should be A. Left skewed.
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  19. #119
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon

    A national TV poll is run asking viewers to ring in regarding whether they think the
    head of the Australian Bureau of Statistics should be sacked over the problems with the
    census. 500,000 people ring in, with 83% of respondents claiming he should be sacked.
    Which one of the following is correct?
    (1 mark)

    A. The biggest problem with this survey is that people under 18 may have responded.

    B. We conclude that majority of Australians believe he should be sacked.

    C. The sample size is large enough to overcome any doubts about the validity of this
    sample.

    D. The results are unreliable as they quite likely suffer from self-selection bias.
    Last edited by davidgoes4wce; 8 Apr 2017 at 12:06 AM.
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  20. #120
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon

    Id rule out D straight away in that question.

    This from Wikipedia:

    "In statistics, self-selection bias arises in any situation in which individuals select themselves into a group, causing a biased sample with nonprobability sampling. "
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  21. #121
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon

    Id rule out A straight up as well, which would love me down to B or C.
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  22. #122
    Executive Member
    Join Date
    Jun 2014
    HSC
    N/A
    Gender
    Male
    Location
    Sydney, New South Wales
    Posts
    1,885
    Rep Power
    4

    Re: University Statistics Discussion Marathon

    Statistical validity refers to whether a statistical study is able to draw conclusions that are in agreement with statistical and scientific laws. This means if a conclusion is drawn from a given data set after experimentation, it is said to be scientifically valid if the conclusion drawn from the experiment is scientific and relies on mathematical and statistical laws.

    id also refer out C, and would go for B in this question.
    | B Eng (Hons) | IB Mathematics SL | IB Mathematics HL | Australian Cricket | Casual University Statistics Tutor

  23. #123
    Supreme Member Flop21's Avatar
    Join Date
    May 2013
    HSC
    2015
    Gender
    Female
    Posts
    2,850
    Rep Power
    5

    Re: Statistics

    is there an easy way to find the probability mass function??

    right now im just looking at example P(X=x) like P(X=1... etc.) and trying to find a pattern

    but this is hard for tricky ones
    2015 HSC: English Adv, Mathematics, Business Studies, Biology, Multimedia.

    HSC Biology Flashcards

  24. #124
    Vexed?
    Join Date
    Sep 2016
    HSC
    N/A
    Gender
    Male
    Location
    Antartica
    Posts
    279
    Rep Power
    2

    Re: Statistics

    Quote Originally Posted by Flop21 View Post
    is there an easy way to find the probability mass function??

    right now im just looking at example P(X=x) like P(X=1... etc.) and trying to find a pattern

    but this is hard for tricky ones
    Got an example question?

  25. #125
    Supreme Member Flop21's Avatar
    Join Date
    May 2013
    HSC
    2015
    Gender
    Female
    Posts
    2,850
    Rep Power
    5

    Re: Statistics

    Quote Originally Posted by He-Mann View Post
    Got an example question?
    A box contains four red and two black balls. Two balls are drawn. Let X be
    the number of red balls obtained. Find fX(x)


    Okay so if I haven't screwed up, P(X=0) = 1/15, P(X=1) = 4/5, P(X=2) = 2/5, and any other value of X, P = 0.

    So how do I put this into a proper answer for this question?
    2015 HSC: English Adv, Mathematics, Business Studies, Biology, Multimedia.

    HSC Biology Flashcards

Page 5 of 11 FirstFirst ... 34567 ... LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •