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ViennaJade

How do you find the P value of a hypothesis test?

  • 10 months ago
  • 10 months ago

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  1. amistre64
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    its the area of the tails ....

    • 10 months ago
  2. amistre64
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    determine the z or t score using the Ha as the cutoff stat for Ho the P-value is just the area left in the tails

    • 10 months ago
  3. ViennaJade
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    This is my particular problem: A survey of 1910 people who took trips revealed that 136 of them included a visit to a theme park. Based on those survery results, a management consultant claims that less than 8% of trips include a theme park visit. Test this claim using the alpha= .01 significance level. Assuming Ho, The z score is? The critical z score for declaring significance is? The P Value of the Hypothesis test is_____?

    • 10 months ago
  4. amistre64
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    are you using a ti83, stat program, or just tables in the book?

    • 10 months ago
  5. amistre64
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    |dw:1370969246279:dw|

    • 10 months ago
  6. ViennaJade
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    I found the z score to be -1.4168...then the critical z score using norm.s.inv(.99) on excel to be 2.32...but I do nt know how to find the p value...would I need to find the z score for .08 and use that value into norm.s.dist(z value, cumulative)? that is what I think to do...but I don't know how to find the z value with P (x<.08)

    • 10 months ago
  7. ViennaJade
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    we have been using excel..wow I am so glad I found this site, I have been searching for a free help site and had no luck

    • 10 months ago
  8. amistre64
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    1910*.08 = 153 use 153 is your test value

    • 10 months ago
  9. amistre64
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    since there is no standard deviation given, should we do a t stat, or a z stat? sample size seems well over 30 to me

    • 10 months ago
  10. ViennaJade
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    what is a t stat?

    • 10 months ago
  11. ViennaJade
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    I believe so...you mean z score?

    • 10 months ago
  12. amistre64
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    its similar to a zscore stat, but uses a t distribution as opposed to a normal distribution .... its used for unknown standard deviations

    • 10 months ago
  13. dumbcow
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    @ViennaJade , Excel gives pvalue of .078 for z-score of -1.4168 "NORMSDIST(-1.4168)"

    • 10 months ago
  14. ViennaJade
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    hmmm dumbcow let me try that

    • 10 months ago
  15. ViennaJade
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    admiter I found the standard deviation by hand

    • 10 months ago
  16. amistre64
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    136/1910 = .0712 as a "mean" this is less then 8% of the sample size already so i don think the score of 8% will be negative

    • 10 months ago
  17. ViennaJade
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    I just checked dumbcow's answer and it was right

    • 10 months ago
  18. ViennaJade
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    now I'm not sure I remember why his answer is right though...

    • 10 months ago
  19. amistre64
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    \[\Large\frac{136}{1910}\pm Z_{.01}\left( \frac{\frac{136}{1910}\frac{1774}{1910}}{\sqrt{1910}} \right)\].01 in one tail is .02 in both tails,relates to a confidence interval of 98%, z=2.33 a confidence interval of 98% is \[\Large .0712\pm 2.33\frac{(.0712)(.9288)}{\sqrt{1910}}\] cows answer was correct, thats nice :)

    • 10 months ago
  20. amistre64
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    opps, forgot to sqrt the whole thing

    • 10 months ago
  21. ViennaJade
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    why are you finding the confidence interval? I'm confused

    • 10 months ago
  22. amistre64
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    so an interval of .057 to infinity .... just trying to recall some stuff. how would you determine the test statistic for less then 8%?

    • 10 months ago
  23. ViennaJade
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    I would want to use the z score formula , plug in 153/1910-.08 all over the standrd dev of .006208

    • 10 months ago
  24. ViennaJade
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    and then use excel =norm.s.dist(the z score)

    • 10 months ago
  25. amistre64
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    .08 - 153/1910 of course the only differnce is a sign

    • 10 months ago
  26. ViennaJade
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    amistre thank you so much for helping me...and dumbow...do you get paid for this?

    • 10 months ago
  27. dumbcow
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    http://en.wikipedia.org/wiki/Statistical_hypothesis_testing#Common_test_statistics this problem is a 1-proportion z test right? \[z = \frac{.08 - \frac{136}{1910}}{\sqrt{\frac{136}{1910}(1-\frac{136}{1910})}}\sqrt{1910}\]

    • 10 months ago
  28. ViennaJade
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    dumbcow I have no idea what that equation is...we were taught that z score of p hat= p hat-Ho/stdev

    • 10 months ago
  29. dumbcow
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    how are you finding std dev?

    • 10 months ago
  30. dumbcow
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    sqrt{n*p*(1-p)}

    • 10 months ago
  31. ViennaJade
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    I don't think it's 1-proportion because they want less than .08

    • 10 months ago
  32. ViennaJade
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    stdev of p hat= sqrt(p*q/n)

    • 10 months ago
  33. ViennaJade
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    p is .08, q is .92

    • 10 months ago
  34. ViennaJade
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    n is 1910

    • 10 months ago
  35. dumbcow
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    oh ok, well in that case you already did everything and didn't need any help :)

    • 10 months ago
  36. ViennaJade
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    I still didn't get how you used the z score I found and used that to find the p(x<.08)? sorry..

    • 10 months ago
  37. dumbcow
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    |dw:1370971511146:dw| the p-value is the probability of being "left" of z-score on the bell curve the excel function "normSDist" will tell you the area "left" of a given z-score

    • 10 months ago
  38. dumbcow
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    if p-value < .01 , reject H0 otherwise Fail to reject H0

    • 10 months ago
  39. ViennaJade
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    I think I get it. Thank you so much Amistre and dumbcow! :))

    • 10 months ago
  40. dumbcow
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    yw

    • 10 months ago
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