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    one sample t-test alternative




    Hello,

    I hope someone can help me, because I am getting crazy with this. Imagine the following scenario: I have several participants. Each participant has 5 scores in 5 different items. The score in each question is either 1 (correct response) or 0 (incorrect response). Basically would be something like this:

    P1 P2 P3 P4
    1 1 1 1
    1 1 1 0
    1 1 0 0
    1 0 0 0
    0 0 0 0


    What I want to explore is whether each participant mean score is bigger than 0.75 (Which would mean a good performance in the task). What can I do?
    Thanks a lot!

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    Re: one sample t-test alternative

    What I want to explore is whether each participant mean score is bigger than 0.75 (Which would mean a good performance in the task).
    According to the title of the thread you want to determine
    whether the mean rate of correct responses is > 0.75?

    If the number of participants is large enough (n > 30 or
    so), then t-test with expected value 0.75 should be possible.
    Or, why do you seek for an alternative?

    With kind regards

    K.

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    Re: one sample t-test alternative

    Quote Originally Posted by Karabiner View Post
    According to the title of the thread you want to determine
    whether the mean rate of correct responses is > 0.75?

    If the number of participants is large enough (n > 30 or
    so), then t-test with expected value 0.75 should be possible.
    Or, why do you seek for an alternative?

    With kind regards

    K.
    thanks for your reply. I look for an alternative because if you see the data are not normally distributed (I only have 0 and 1).

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    Re: one sample t-test alternative

    According to your description, your dependent variable is not 0/1 but on a scale from 0 to 5
    (total number of correct responses) or from 0.0 to 1.0 (total number of correct responses
    divided by 5), respectively.

    With kind regards

    K.

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    Re: one sample t-test alternative

    So maybe I am overcomplicating this. Yes, my DV is the proprortion of correct responses for each participants. So yes, I think that as long as the data are normally distributed I can use a one sample t-test right?

    Thanks

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    Re: one sample t-test alternative

    So far I am agreeing with Karabiner. Plot and test these data for normality to better understand the distribution.
    Stop cowardice, ban guns!

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    Re: one sample t-test alternative

    Quote Originally Posted by ajestudillo View Post
    So maybe I am overcomplicating this. Yes, my DV is the proprortion of correct responses for each participants. So yes, I think that as long as the data are normally distributed I can use a one sample t-test right?

    Thanks
    If sample size is large enough, then the t-test is considered
    robust against non-normality.

    With kind regards

    K.

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    Re: one sample t-test alternative

    Thanks to both!

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    Re: one sample t-test alternative

    By the way, something that I am not sure if it was clear enough is that I am treating each participant as a different measure: I don't want to explore whether the overall performance of all the participant is bigger than.75. I want to explore whether the score of each of the participants is bigger than .75. Don't know if this changes the thing...

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    Re: one sample t-test alternative

    So you calculate the correct responses/all responses ratio
    for each participant and look whether this is > 0.75 or
    not. Then you can say how many subjects were > 0.75 or
    <= 0.75, respectively.


    With kind regards

    K.

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    Re: one sample t-test alternative

    hi,
    just a really stupid question: why do you need statistics to check this?

    regards
    rogojel

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    Re: one sample t-test alternative

    Thanks again. I think that the best is just to describe the results in terms of ratio.

    Rogojel , basically I wanted something to powerful enough to support my hypotheses.

    Thanks to both.

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    Re: one sample t-test alternative

    yes,
    that is clear. The question is mre about what your hypothesis is. A t test would be appropriate if you had a hypothesis about a population of which your subjects woukd be a sample and you would want to prove that the population has a performance ratio of 0.75 or higher.

    E.g. your population are all the (hypothetical) operators who received a certain kind of training - and you want to prove that the training has the effect of raising the test rate.

    If your hypothesis is about each individual I believe a t-test wil not gve you the right answer, and possibly a false one, because it implicitely refers to a population and a sample of that population.

    kind regards
    rogojel

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    Re: one sample t-test alternative


    Quote Originally Posted by ajestudillo View Post
    Each participant has 5 scores in 5 different items. The score in each question is either 1 (correct response) or 0 (incorrect response). Basically would be something like this:

    P1 P2 P3 P4
    1 1 1 1
    1 1 1 0
    1 1 0 0
    1 0 0 0
    0 0 0 0

    What does these numbers represent? I can only see 4 columns. Is that 4 answers? Or is that 4 participants that has one row for each answer?

    (In statistics it is more common to have each respondent=observation as one row and each column for each question.)



    Quote Originally Posted by ajestudillo View Post
    What I want to explore is whether each participant mean score is bigger than 0.75 (Which would mean a good performance in the task). What can I do?

    For 5 questions I can imagine this number of correct answers: 0, 1, 2, 3, 4, 5.

    The proportion correct answers would be: 0, 0.20, 0.40, 0.60, 0.80, 1.00.

    Why ask for proportion larger than 0.75?

    Do theses questions differ in difficulty? So that question 1 only 10% would answer correct, while in question 5 maybe 70 could be correct?

    - - -

    Or is it that simple, to just count the number of correct answers an note that participant 1 has got 4 of 5 questions correct, thus 80%, and thus been "good"?

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