4 MCQs in Statistics ...

5. In conducting research that looks at differences in populations, samples are used for numerous reasons. Using entire populations in a test is difficult, so various sampling techniques are applied. In situations in which the population variance is unknown, the Student t distribution is often used. To use this distribution, certain assumptions must be made. Which of the following statements is not correct? a. The t distribution is a family of distributions. b. It is a symmetrical, mound shape distribution. c. It is a continuous distribution. d. It has less spread than the standard normal distribution. 

6. The Ohio State Patrol has identified eight intersections in Clermont County of high risk, due to the number of accidents. To address these concerns, the state patrol wants to make some changes in the traffic light patterns at these intersections. A proposal was developed to do a 4-month test of these changes at the eight intersections to see whether a significant decrease in accidents occurred. The number of accidents 2 months before the modifications at the eight intersections was 57 and the number of accidents 2 months after the modification was 37. To conduct the test, the .01 significance level was selected. The test statistic was -2.415. What would be the critical value for the test decision to be made? a. 2.624 b. -2.998 c. 2.947 d. 2.602 

7. Historically, single-income households or individuals have made up about 27 percent of the housing market. A sample of 80 recent mortgages indicated that 24 single-income families or individuals purchased a new home. Has there been a change in this historical belief? a. The market has not changed. b. The market is generally difficult to predict due to the changing economy. c. The market has changed. d. More information is needed to make any statement. 

8. A business owner is trying to decide between three different ads for the yellow pages. The ads are of different sizes and costs. The owner wants to get the best deal possible to save money, but wants to effectively reach potential customers. The question is whether there is a significant difference between the three different ads in their effectiveness in reaching customers. To make a more informed decision, the manager should choose which statistical test? a. Linear regression correlation b. Goodness-of-fit test c. Simple linear regression d. Analysis of variance (ANOVA)