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Type 1 sampling error

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  • Type 1 sampling error

    Type 1 sampling error is classified as:
    A. Alpha error
    B. Beta error
    C. Gamma error
    D. Delta error
    Ans. A
    Alpha (α) is the probability of making a Type I error while testing two hypotheses.
    Alpha represents an area were two population distributions may coincide. Data that fall within this area may pertain either to one or the other population. Thus, deciding whether the data are representative of one or the other is subjected to two types of error:
    A Type I error is made when we decide that the data is representative of one population (typically phrased as the alternative hypothesis) and not the other (typically phrased as the null hypothesis) when the data is, indeed, representative of the latter. Said otherwise, we make a Type I error when we reject the null hypothesis (in favor of the alternative one) when the null hypothesis is correct.
    The alpha level (α) is the probability we want to have, thus determined beforehand, of making such error. It is conventionally set at 5% (ie, α = 0.05), indicating a 5% chance of making a Type I error.
    The alpha level also informs us of the specificity (= 1 - α) of a test (ie, the probability of retaining the null hypothesis when it is, indeed, correct).
    A Type II error is made when we decide that the data is representative of one population (typically phrased as the null hypothesis) and not the other (typically phrased as the alternative hypothesis) when the data is, indeed, representative of the latter. Said otherwise, we make a Type II error when we fail to reject the null hypothesis (in favor of the alternative one) when the alternative hypothesis is correct.
    The beta level (β) is the probability we want to have, thus determined beforehand, of making such error. It is conventionally set at 10% (ie, α = 0.10), indicating a 10% chance of making a Type II error.
    The beta level also informs us of the power (= 1 - β) of a test (ie, the probability of accepting the alternative hypothesis when it is, indeed, correct).
    [LEFT][LEFT][FONT=&quot]NOYMER Andrew (undated). Alpha, significance level of test. In, Paul J LAVRAKAS (undated). Encyclopedia of survey research methods.
    Last edited by Parveen Komal; 03-06-2014, 05:55 PM.
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