1. Intro to Stats and Collecting Data

Discuss why the order of questions or choices within a questionnaire are important in sample surveys.

Platelet-Rich Plasma In a prospective cohort study, 20 patients with alopecia (hair loss) had platelet-rich plasma (PRP) injected in their scalps. After three months, the mean difference in hair density (after - before) was 170.70 hairs per square centimeter with a standard deviation of 37.81hairs/cm2. Source: Gkini MA, Kouskoukis AE, Tripsianis G, Rigopoulos D, Kouskoukis K., “Study of Platelet-Rich Plasma Injections in the Treatment of Androgenetic Alopecia through a One-Year Period”. J Cutan Aesthet Surg, 2014; 7:213–219.

a. What does it mean for this study to be a prospective cohort study?

An office manager wants to determine how employees feel about their personal growth and professional achievement in the last quarter. Should they run an observational study or experiment?

Write Your Own Survey Develop a survey that you could administer using online survey tools such as StatCrunch, surveymonkey.com, or polldaddy.com. Administer the survey. Did the responses accurately reflect the goals of each question? What types of nonsampling error did you encounter in the survey? If you invited individuals to take the survey via an e-mail, what type of response rate did you obtain? What approach did you take to increase response rate?

Determine whether the data set is a population or a sample. Explain your reasoning.

The annual revenue of each team in a pro sports league

Determine whether the survey question is biased. If the question is biased, suggest a better wording.

How does the media influence the opinions of voters?

In Exercises 9 and 10, determine whether the study is an observational study or an experiment. Explain.

To study the effect of using digital devices in the classroom on exam performance, researchers divided 726 undergraduate students into three groups, including a group that was allowed to use digital devices, a group that had restricted access to tablets, and a control group that was “technologyfree.” (Source: Massachusetts Institute of Technology)

Determine whether the study is an observational study or an experiment. Explain.

A research study compared the memory retention of subjects when a learning activity was followed by a brief period of wakeful rest and when a learning activity was followed by a brief period of distraction. (Source: Springer Nature)

A store surveys its target demographic and learns that 86% of people would purchase the product they’ve been heavily advertising. Is this an experiment or an observational study? Can they conclude their current advertising strategy caused the high percentage of interest?

Determine whether the survey question is biased. If the question is biased, suggest a better wording.

How many hours of sleep do you get on a normal night?

"Determine whether the statement is true or false. If it is false, rewrite it as a true statement.

It is impossible to obtain all the census data about the U.S. population."

Determine whether the survey question is biased. If the question is biased, suggest a better wording.

How much do you exercise during an average week?

Determine whether the study is an observational study or an experiment. Explain.

A study used periodic blood pressure readings and brain MRIs of adults to find that adults with long periods of high blood pressure were more likely to develop cerebral small blood vessel disease. (Source: American Heart Association)