Exam 1: Collecting Data

Use the following A tree enthusiast is interested in estimating the typical length of oak tree leaves. He chooses 30 leaves from the oak tree in his backyard. -Is this a biased sampling strategy? If so, identify a population that we can generalize to, given our sample.

Use the following A university's Admissions staff sends one of four different representatives to work at college fairs. A study was conducted to evaluate the relative effectiveness of the four representatives. For each college fair over the course of the year, the number of inquiries from students, the type of fair (large or small), the representative who worked at that fair, and the percent of inquiries that resulted in applications were recorded. It was found that one of the representatives was far more effective at getting lots of inquiries. -Is this an observational study or an experiment? Briefly justify your answer.

Use the following to A realtor's website provides information on area homes that are for sale. Identify each of the variables as either categorical or quantitative. -Style: the style of home (ranch, Cape Cod, Victorian, etc.)

Refer to the variables collected by the high school senior looking at colleges. Identify a question we might ask about any one of these individual variables.

Use the following In each situation, indicate whether the method of data collection is biased. If it is, briefly explain why. -A reporter from the campus newspaper is writing an article about student opinions on Greek organizations (sororities and fraternities). For his article, he visits all of the Greek houses on campus and interviews a random sample of residents of each house.

A company is interested in redesigning its website, and two possible designs are being considered. The company wants to get input in the form of ratings of the two designs. Design a matched pairs experiment to decide which design gets higher ratings. Fifty volunteers are available to participate.

Use the following A tree enthusiast is interested in estimating the typical length of oak tree leaves. He chooses 30 leaves from the oak tree in his backyard. -What is the sample in this situation?

A group of students were asked to count the number of scars on both of their hands. The number of scars on their dominant hand was compared to the number of scars on their "off" hand. Is this an observational study or a randomized experiment?

Use the following The USStates dataset, used throughout the textbook, contains information on the 50 U.S. states from 2008. A small segment from the dataset is displayed in the following table. -What are the cases in this datatset?

Use the following A university's Admissions staff sends one of four different representatives to work at college fairs. A study was conducted to evaluate the relative effectiveness of the four representatives. For each college fair over the course of the year, the number of inquiries from students, the type of fair (large or small), the representative who worked at that fair, and the percent of inquiries that resulted in applications were recorded. It was found that one of the representatives was far more effective at getting lots of inquiries. -What are the variables recorded in this study? List them and identify each as either categorical or quantitative.

Refer to the variables provided by the realtor. Identify a question that we might ask about relationships between any two (or more) of these variables.

Use the following A group of researchers investigated the effect of media usage (whether or not subjects watch television or use the Internet) in the bedroom on "Tiredness" during the day (measured on a 50 point scale). -To collect these data, the researchers randomly selected homes to visit and interviewed the adult member of the household whose birthday was nearest. Is this an experiment or an observational study? Briefly explain.

Use the following A group of researchers investigated the effect of media usage (whether or not subjects watch television or use the Internet) in the bedroom on "Tiredness" during the day (measured on a 50 point scale). -Identify the variables as either explanatory or response variables.

The ____________________ variable is used to understand or predict values of the ________________________ variable.

Use the following to answer questions : The Admissions Office at a small university has developed a new 10-minute video about the university to send to prospective students. Before mass-producing the DVD, they would like to test whether it is more effective than the current video. Suppose that you have 12 high school student volunteers who have agreed to take part in an experiment. The explanatory variable to be studied is the type of video, with two levels OLD and NEW. -Would you describe your study as a randomized comparative experiment, a matched pair experiment, or an observational study? Briefly explain..

Use the following In each situation, indicate whether the method of data collection is biased. If it is, briefly explain why. -A campus bookstore is holding a drawing to give away five free textbooks (one per student). Students enter the contest by writing their name and contact information on an index card. The index cards were placed in a bowl, thoroughly mixed around, and five cards were selected. Those five students were contacted and received their free textbook.

Use the following to A realtor's website provides information on area homes that are for sale. Identify each of the variables as either categorical or quantitative. -School District: the school district in which the home is located

Use the following Identify whether each of the following scenarios describe a randomized comparative experiment or a matched pairs experiment. -Studies have shown that multi-tasking typically results in lower productivity. However, some people believe that individuals who play video games are better at multi-tasking. To investigate this, 28 video game players were randomly assigned to one of two groups. One group was assigned to play a video game that involved driving a car around a track. The other group was assigned to play the same video game while simultaneously answering unrelated trivia questions over the phone.

In elementary school (Grades 1 through 6) there is a strong association between a child's height and reading ability. What is a possible confounding variable that would help explain this relationship? Explain briefly.

Is using meditation to relax and clear the mind a natural way to treat insomnia? Design an experiment to investigate this question. Assume that you have 20 individuals who suffer from insomnia available to participate in the study. At the end of two months, you will ask subjects to rate their sleep quality.