Explain the relationship between a sample and a population.
What is the explanatory variable?
What is the response variable?
What are the experimental units?
What is a possible confounding variable?
A random sample of 200 patients is taken from a large medical clinic to determine if taking an omega-3 fish oil tablet daily lowers cholesterol levels. The patients are separated into groups by gender and then a blind study is administered, giving 1/2 of each group the fish oil and 1/2 of each group a placebo. The study found that those who took the fish oil tablet lowered their cholesterol levels more than those who had taken the placebo.
What is the exploratory variable?
What is the reponse variable?
What are the experimental units?
Juan conducted two different surveys about student transportation to school. For Survey A, he stood at the entrance of the school at 7:30 a.m. and surveyed the first 80 students. For Survey B, he used a random number generator to select 80 students in the school to survey.
Describe the sampling technique in survey A.
Describe the sampling technique in survey B.
Identify which survey Juan should have more confidence in and explain why.
Suppose a high school guidance counselor wants to find out the proportion of the students at his high school who have tried alcohol. He sends out an email to 200 randomly chosen students and asks them if they have tried alcohol. Of the 92 that responded, 6% said that they tried alcohol.
Describe how NONRESPONSE bias might lead to bias in this survey.
Describe how RESPONSE bias might lead to bias in this survey.
Is the sample proportion of 6% likely greater than or less than the actual proportion of the students at the school who have tired alcohol? Explain your answer.
What is a possible confounding variable?