Categorize the descriptions according to the data collection method they describe.
A sample from a neightborhood is asked if they want more streetlights on the street.
A researcher collects existing data and draws conclusions.
A sample is taken from a population and asked questions.
People are asked to attend a meeting to discuss the need for new street lights.
A population is divided into groups. Each group receives a different treatment, and the results are compared.
The number of accidents on the street is compared to last year's rate.
Streetlights are installed on one street and people are then asked if they like the change.
Experiment
Observational Study
Sample Survey
Categorize each description based on similarities between data collection methods.
can be carried out without the sample knowing who the researcher is
yields more accurate results with larger sample sizes
the researcher must interact with the sample being studied
collect data already in existence
care must be taken to avoid bias
Both sample surveys and experiments
Both experiments and observational studies
Both observational studies and sample surveys
All data collection methods
Which TWO sampling methods involve the highest risk of bias?
Dr. Demo wants to perform a clinical trial for a new drug. He has collected consents from one hundred patients. He will have 50 patients take the drug, and 50 patients take the placebo.
Which of the following selection methods introduces significant bias to his experiment? Select four.
Managers of a forest reserve want to know what percent of the visitors with dogs keep their dogs on a leash. The park assigns an employee to count the numbers of visitors that do and do not use a leash.
What type of study is this?
A local newspaper polls citizens of a city about the construction of a new high school.
What type of study is this?
Where does randomness come into play when designing a study (surveys, experiments, or observational studies)?
Answer in full English sentences.
A civil engineer is conducting a survey to find out if city residents want the road widened for increased traffic flow. He conducts his survey by waiting at an interesection in the morning and asking his questions to vehicles stopped at the red light.
Is the data collected from this survey representative of the city's opinion? If not, where is the bias? What should the civil engineer do to reduce bias?
One point per question.
A grocery store surveys every fifth customer to determine whether it should consider expanding its organic foods department. The results are shown in the table.
Does the sampling method introduce bias? Why or why not?
About what percent of the customers favor the expansion?
Round your answer to the nearest percent.
