# l3 - STAT 350 Fall 2008 Var1 The actual distribution of...

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STAT 350 – Fall 2008 Lab #3 - SOLUTION Var1 The actual distribution of these sample points is Binomial(n = 30, π = 0.3) Lab #3 – Solution Page 1 of 5 12 10 8 6 4 9 8 7 6 5 4 3 2 1 0 var1 Frequency Mean 8.5 StDev 2.038 N4 0 Histogram of var1 Normal 16 14 12 10 8 6 4 2 99 95 90 80 70 60 50 40 30 20 10 5 1 var1 Percent Mean 8.5 StDev 2.038 0 AD 0.692 P-Value 0.065 Probability Plot of var1 Normal - 95% CI a. Looking just at the histogram, would you feel comfortable saying this sample came from a normal distribution? ( There really are no right or wrong answer – this is a judgment call, I just want you to think about it. ) The histogram looks a little too skewed to be normal, but aside from a little skewness, it doesn't seem all that far from normal. .. b. Looking just at the probability plot (don't look at the information on the right side of the table), would you feel comfortable saying this sample came from a normal distribution? ( There really are no right or wrong answer – this is a judgment call, I just want you to think about it. ) The points are within the confidence bounds, so it seems okay. There is an odd pattern, but that's caused by having integers. (Notice if the distribution is Normal, but we round to integers, we will still get this effect) c. According to the p-value on the probability plot, can we say this sample came from a normal distribution? The p -value is 0.065. So that suggests the evidence is not strong enough to say this does NOT come from a Normal distribution. d. If your answer to part (c) was "no", describe how the probability plot deviates from normal and compare this to how the histogram appears to deviate from the normal. It might help to also examine the original data. N/A based on my answer to (c). Answers may vary.

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Var2 The actual distribution of these sample points is Normal( μ = 50, σ = 15) Lab #3 – Solution Page 2 of 5 80 60 40 20 6 5 4 3 2 1 0 var2 Frequency Mean 51.13 StDev 17.28 N1 5 Histogram of var2 Normal 120 100 80 60 40 20 0 99 95 90 80 70 60 50 40 30 20 10 5 1 var2 Percent Mean 51.13 StDev 17.28 5 AD 0.455
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## This note was uploaded on 02/23/2009 for the course STAT 350 taught by Professor Staff during the Fall '08 term at Purdue University.

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l3 - STAT 350 Fall 2008 Var1 The actual distribution of...

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