# Statistics

Date File 1

Chapter One

1) Determine whether the evaluated group is a population or a sample
a) Based on a randomly selected group of 500 patients with high cholesterol, it was found that 67% have heart disease.   Is this a population or a sample; explain your answer.
This is a sample. The study looked at 500 patients with high cholesterol, not ALL patients with high cholesterol.
b) An investigation of 150 randomly selected local restaurants concluded that 42% of local restaurants have serious health code violations.   Is this a population or a sample; explain your answer.
This is a sample. The study looked at 150 randomly selected restaurants, not ALL restaurants.
2) Determine whether the given value is a statistic or a parameter.
c) A researcher determines that 42.7% of all downtown office buildings have ventilation problems.   Is this a statistic or a parameter; explain your answer.
The 42% is a statistic, and the ventilation problems is a parameter. The parameter is what part of the sample/population is being studied, while the statistic is the information that is inferred from that study.
d) After taking the first exam, 15 of the students dropped the class.   Is this a statistic or a parameter; explain your answer.
I believe the 15 students is a statistic (although incomplete), and the fact that they dropped the class is the parameter. We are looking at “students who dropped the class” in this study, which would be the parameter. I say that the statistic is incomplete, because we don’t have all the data; How many students total are there? Is this 15 percent in one class or all versions/schedules, etc?
3) Identify the type of sampling used.
e) A tax auditor selects every 1000th income tax return that is received.   What type of sample is this and why?
This is a systematic sample. I know this because in a systematic sample, every Nth element is “tested”. In this case, every 1000th tax return is audited.
f) The name of...