A school psychologist wants to test the effectiveness of a new method for teaching reading. She takes 500 first grade students from District 12 (all with the same teacher), and randomly assigns half of them to the traditional method and half of them to the new method for teaching reading. The students are not told which teaching method they are being taught with. At the end of the year, she obtains all scores on a reading achievement test, and looks for any differences between the two groups. a. What is the research objective? b. What type of study was used? Give the exact name. c. Does this study make use of random sampling, random assignment, both, or neither? How do you know? d. What are the explanatory and response variables? Explanatory Variable: Response Variable: e. What are the treatments? e. Was blinding used? If so, how?

The medical researcher is comparing two treatments for lowering cholesterol:  diet and meds.  The researcher wants to see if the patients who receive the recommendation to change their diet have equal success lowering cholesterol compared to a prescription of meds.  A random sample of some patients who received the recommendation to change their diet and others who were prescribed meds was taken.  The results of how many did or did not lower their cholesterol are shown below:   Diet Meds Yes 372 561 No 169 308 What can be concluded at the  = 0.10 level of significance?       The test statistic  z= (please show your answer to 3 decimal places.) The p-value = (Please show your answer to 4 decimal places.)

A company wishes to evaluate the effect of package design on one of its products, a certain brand of cereal. The four package designs are to be tested in different stores throughout a large city. There are 20 stores available for the study. The amount of cereal sold is known to vary depending on the size of the stores. The 20 stores are divided into five groups of four stores each by size. The following sales figures ($1000s) were obtained after a 1-month period. Stores Design A Design B Design C Design D 1 40 33 37 38 2 45 27 32 40 3 43 31 30 41 4 44 38 40 42 5 56 45 49 42 Enter the above data into a suitable software and then conduct an analysis of variance without blocking to test whether there is evidence of a significant difference in mean sales of different package designs. Use alpha=0.01. What is the conclusion for the null hypothesis that all treatment means are equal? O Do not reject HO. There is sufficient evidence to conclude that the average sales for all stores are not…

A company wishes to evaluate the effect of package design on one of its products, a certain brand of cereal. The four package designs are to be tested in different stores throughout a large city. There are 20 stores available for the study. The amount of cereal sold is known to vary depending on the size of the stores. The 20 stores are divided into five groups of four stores each by size. The following sales figures ($1000s) were obtained after a 1-month period. Stores Design A Design B Design C Design D 1 40 33 37 38 2 45 27 32 40 3 43 31 30 41 4 44 38 40 42 5 56 45 49 42 Enter the above data into a suitable software and then conduct an analysis of variance with blocking (analyze this data as a complete block design) to test further whether there is evidence of a significant difference in mean sales of different package designs. Use alpha=0.01. What are the sums of squares for Blocks? Provide your answer to the nearest 2 decimal places.

Rita has two ways to travel from her home in Norco to her office in Los Angeles. One is to go via the 10 Freeway, and the other is to go via 60 Freeway. In order to determine which way she should travel on a daily basis, Rita has recorded the travel times for samples of twelve trips via the 10 Freeway and twelve trips via the 60 Freeway. The following table gives the travel times (in minutes) for the twenty-four trips.   Travel times in minutes 10 Freeway 66, 70, 73, 71, 72, 71, 65, 74, 69, 71, 75, 71 60 Freeway 77, 72, 71, 68, 74, 80, 70, 78, 76, 71, 68, 67 Assume that the two populations of travel times are normally distributed and that the population variances are equal. Can we conclude, at the 0.01 level of significance, that the mean travel time via the 10 freeway, μ1, is different from μ2, the mean travel time via the 60 freeway? Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and…

A researcher wanted to test whether people tended to trust people who smiled more than people who did not smile. To test that, she collected a sample of fifty people and presented each of them with 48 pairings of photos. Each pairing was made of one photo of a smiling person, and another photo of a person who was not smiling. The subjects were asked to select the person they trusted more. For each subject, the researcher measured the number of times a smiling person was selected. Based on the null hypothesis, what should be the mean number of times a smiling person is selected? 1. 48 2. 25 3. 50 4. 24

Dorinda is in second grade. She asks 6 of her classmates if they like to wear friendship bracelets. Four of her classmates said yes. Based on her findings, would it be reasonable to assume that about 2/3 of the pupils at her school (which has kindergarten through fifth grade) would also like to wear friendship bracelets? Why or why not?

Suppose you were going to conduct a survey of visitors to your campus. You want the survey to be as representative as possible.   How would you select the people to survey?   Why would that be your best method?

Mandrake Falls High School is providing a weekend course in laboratory techniques to its laboratory students. Of the 200 students enrolled in lab classes at Mandrake, 75 have taken the weekend course. Mandrake is evaluating the course's effectiveness by having its lab instructors record harmful lab "incidents": accidents, misuse of lab equipment, etc. The contingency table below gives a summary of the data that have been gathered so far for Mandrake's 200 lab students. Each student is classified according to two variables: status regarding lab techniques course ("Took the course" or "Didn't take the course") and laboratory performance ("Involved in no incident", "Involved in exactly one incident", or "Involved in 2+ incidents"). In the cells of the table are the respective observed frequencies. Note that three of the cells also have blanks. Fill in these blanks with the frequencies expected if the two variables, status regarding lab techniques course and laboratory performance, are…

Many students at Matt's school claim they can think more clearly while listening to their favorite kind of music. Matt thinks music interferes with thinking clearly. To test this, he recruits 84 volunteers and randomly assigns them to two groups. The “Music” group listens to their favorite music while playing a “matching” memory game. The “No Music” group plays the same game in silence. Below are summary statistics for the number of turns it took each subject to complete the game (fewer turns indicates a better performance). (a) Is there convincing evidence that listening to music increases the number of turns required to finish the memory game? (b) Suppose Matt allowed people to choose whether or not they were in the group that listened to music while playing the game? Give an example of a problem that might arise if the subjects were allowed to do this.