Q3) In a difference of proportion test with alpha= .01, the critical value for a one tailed lower test is/are: A) -1.96 B) -1.645 and 1.645 C) -2.33 D) -1.28
Q4) If the test statistic for a small sample difference of means test is t*=-2.15, we could reject the Null Hypothesis at alpha =.01 for a two tailed test with degrees of freedom equal to 20: true or false
Q9) In a difference of MEans test there are two sources of variability that must be considered to calculate the standard error: True or false
Q6) For a small sample difference of means test where n1 = 20 and n2 = 20, and we can assume the population variances are equal, the formula for the pooled variance is: A) (s1+s2)/(n1+n2) B)(s1^2 + s2^2)/2 C)(s1^2 + s2^2)/(n1+n2) D) (s1+s2)/2
Q10)When we pool the variance in a difference of means problem, it changes the way the degrees of freedom are calculated (compared to situation when we don’t pool the variance). True or false
Q24)A covariance coefficient is bounded between 1 and -1. True or false
Q27)A correlation coefficient shows both strength and direction of a linear relationship. True or false
Q29) A regression analysis was done of residential property values in a city based on 157 properties. The independent variable used to predict the Sale Price (Y) is Square Footage (X). The estimated regression equation is: Y = 96,600 + 22.5X R-square = .77 Where Y= Sale Price X = Square Footage.
Interpret the value of R-square. :
|A) We are 77% confident that Square Footage is linearly related to Sale Price (Y).|
|B) 77% of the observed sale process will fall within two standard deviations from the least squares line.|
|C) 77% of the variability in Sale Prices can be explained by Square Footage|
D) There is a moderately strong negative correlation between Sale Price and Square Footage.
Q30) A regression analysis was done on 81 different SUV vehicles. The variables analyzed Included are the average gas mileage in miles per gallon (Average MPG) and the engine size in liters (Engine Size). The average miles per gallon is a weighted average of city and highway driving to reflect a 40/60 percent split.
The estimated regression equation is: Average MPG = 27.654 - 2.114*Engine Size
R-squared = .4615
Based on this result, the correlation between Average MPG and Engine Size is:
Q 3) For left tailed test at 1% significance level, the critical value of Z is -2.33 (From Standard normal table)
Answer: Option C) -2.33
Q 4) test statistic t* = -2.15
Df = 20
Two tailed test,
The critical value of t for two tailed test with 20 df at 1% significance level is +/-2.845
Since |t| calculated is less than |t| tabulated . Fail to Reject H0
Q9) In a difference of MEans test there are two sources of variability that must be considered to calculate the standard error:
The pooled variance is
Answer: Option B)
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