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In a normal distribution, moving 2 standard deviations on both sides of the mean encompasses what percentage of the scores? 

According to your book, an extraneous variable is one that is not part of your study but can potentially affect the results of the study.

As discussed in class, what is the most common mistake made when composing survey questions?

A researcher is working with a data set that includes an even number of scores. What is the procedure for identifying a median value? 

A community college uses three different methods of instruction (face-to-face, online, and hybrid) in its classes. The president of the college would like to know if there is a difference in student outcomes for the three methods. To test the question, a random sample of 24 students (8 from each method of instruction) was selected and their scores from a common final exam were compared using ANOVA.   Question: In an effort to reduce administrative and staffing complexity, the college is considering dropping hybrid courses and just offering face-to-face and online classes. Based on the result of your ANOVA test in the previous question, would the college be justified in eliminating hybrid courses, or does your test indicate follow-up investigation of the three instructional methods is needed? Briefly explain your answer, from a statistical perspective.

The table below lists the average number of new homes sold per month by a local real estate firm using three different advertising strategies (A, B, and C).   Advertising Strategy Average Home Sales (per month) A 15 B 25 C 22   Furthermore, assume the least significant difference (LSD) for this test equals 5. [Note: You do NOT need to calculate LSD. The value of LSD is given.] Compare all 3 advertising strategies and determine which methods are significantly different (or not). Finally, briefly explain your overall advice (statistically speaking) to the real estate company regarding the use of these advertising strategies.

A community college uses three different methods of instruction (face-to-face, online, and hybrid) in its classes. The president of the college would like to know if there is a difference in student outcomes for the three methods. To test the question, a random sample of 24 students (8 from each method of instruction) was selected and their scores from a common final exam were compared using ANOVA.   Question: USING THE NUMBERS YOU COMPUTED IN THE PREVIOUS QUESTION, conduct a 7-step hypothesis test (95% confidence) to determine if there is a significant difference in final exam grades between the 3 methods of instruction.

Below is a table for a Randomized Block ANOVA looking for differences in computer prices based on two factors: size of hard drive and amount of RAM. Analysis of Variance Sum of Squares for a RB ANOVA test Source DF SS MS F-Value P-Value  Hard Drive 3 820.4 273.47 4.99 0.045  RAM 2 1108 554 10.10 0.012 Error 6 329 54.83     Total 11 2257.4         Question (fill in the blanks): Based on the numbers in the table above, fill in the amounts for the three remaining “sums of squares” (SS) if we had NOT included “RAM as a second factor in this model? That is, what would SS Hard Drive, SS Error, and SS Total equal if RAM had not been included as a second explainer in this model? SS Hard Drive = [SShd], SS Error = [SSerror], SS Total = [SStotal]    

Is there a link between the number of advertisements (x-variable) a local gym places on billboards and the number of new members who sign up (y-variable)? You collect the following information from a random sample of six months of data from the gym:   Month New Members [Y] Monthly  Ads [X] xy x2 February 45 2 90 4 March 60 3 180 9 May 80 10 800 100 June 62 3 186 9 August 71 8 568 64 October 66 4 264 16      Question: Compute b0 and b1 to construct the least squares regression equation (the y-hat line) describing the relationship between monthly billboard advertisements and new members. [Show as much work as you reasonably can.]  

According to chapter 6, which of the following terms “tells a story by presenting events in an orderly, logical sequence”?