Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    2
    ReputationRep:
    When performing chi squared statistical test, how do you know what the results you expect are?


    Posted from TSR Mobile
    Offline

    11
    ReputationRep:
    You have to assume independence and you multiply the probabilities together and then multiply by the sample size:

    P(going to zoo) = 1/10
    P(going to park) = 4/10

    P(zoo & park) = 0.1 x 0.4 = 0.04 <- Probability that a randomly selected person goes to the park and the zoo, multiply by 10 to get expected value.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Albino)
    You have to assume independence and you multiply the probabilities together and then multiply by the sample size:

    P(going to zoo) = 1/10
    P(going to park) = 4/10

    P(zoo & park) = 0.1 x 0.4 = 0.04 <- Probability that a randomly selected person goes to the park and the zoo, multiply by 10 to get expected value.
    So on my example it's birds feeding from different feeders

    Feeder A 53 birds
    B 43 birds
    C 30 birds

    How do I approach that?


    Posted from TSR Mobile
    Offline

    11
    ReputationRep:
    (Original post by wrnicholls)
    So on my example it's birds feeding from different feeders

    Feeder A 53 birds
    B 43 birds
    C 30 birds

    How do I approach that?


    Posted from TSR Mobile
    Well assuming that the birds are all of the same type, there would only be 1 row/column. which means your expected would be the same as your observed, meaning that chi-squared is 0.
    Offline

    2
    ReputationRep:
    Your expected is number of observations/number of categories. So it would be (53+43+30)/3 because there are 3 feeders. It will be the same for a three feeders.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Tabers)
    Your expected is number of observations/number of categories. So it would be (53+43+30)/3 because there are 3 feeders. It will be the same for a three feeders.
    Ok so you expect the mean of the values you measure?


    Posted from TSR Mobile
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Brussels sprouts
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.