Definitions
The science of collecting, organizing, analyzing, and interpreting data to make decisions.
Statistics
How does a sample differ from a population?
A sample is a subset, or part, of a population.
In 2019, the United States imported more than $4.8 billion worth of personal protective equipment.
Does the number describe a parameter or a statistic? Explain why.
Parameter
The value $4.8 billion is a numerical description of the total amount of personal protective equipment imported
Identify the sampling technique used.
Using random digit dialing, researchers ask 987 U.S. adults whether they feel comfortable with their current financial plans for retirement.
Simple Random Sampling
Determine whether the following example is qualitative or quantitative. Explain why.
The ages of a sample of 350 employees of a software company.
Quantitative
Ages are numerical measurements
The repetition of an experiment under the same or similar conditions.
Replication
A survey of 1025 U.S. adults found that they visited the library an average of 10.5 times in the past 12 months.
Identify the sample in this scenario.
The responses of the 1025 U.S. adults
In a survey of 1000 household food purchasers, 24.7% say that they avoid meat, dairy, and eggs produced by animals living in confined conditions.
Does the number describe a parameter or a statistic? Explain why.
Statistic
The value 24.7% is a numerical description of a sample of household food purchasers
Identify the sampling technique used.
Law enforcement officials stop and check the driver of every third vehicle for blood alcohol content.
Systematic Sampling
Determine whether the following example is qualitative or quantitative. Explain why.
The marital statuses of the employees of a casino.
Qualitative
Martial statuses are attributes
A count or measure of an entire population.
Census
Eighty-three doctors working in the St. Louis area were surveyed concerning their opinions on health care reform.
Identify the population in this scenario.
The responses of all of the doctors working in the St. Louis area
In a sample of 2061 U.S. workers, 39% say that they are engaged in their work.
Does the number describe a parameter or a statistic? Explain why.
Statistic
The value 39% is a numerical description of a sample of U.S. workers
Identify the sampling technique used.
A study in a district of Northern Ethiopia is designed to investigate the level of awareness among pregnant women of the danger signs of obstetrics. Researchers interview all pregnant women in eleven randomly selected neighborhoods in the district.
Cluster Sampling
Determine whether the study is an observational study or an experiment. Explain.
Researcher conduct a study to determine whether a medication based on fish oil known as omega-3 carboxylic acids is effective in reducing the risk of cardiac events in people already at risk. In the study, 13,078 patients are randomly chosen to receive either omega-3 carboxylic acids or a placebo or corn oil daily. Researchers compare the number of cardiac events of the two groups over similar follow-up periods of time.
Experiment
A treatment (omega-3 carboxylic acids) is being applied along with the use of a placebo and random sampling. Researchers are involved in the study.
Occurs when an experimenter cannot tell the difference between the effects of different factors on the variable.
Confounding Variable
In a survey of 23,503 U.S. adults, 59% of them said that if they were single, they would look up someone on the Internet before going on a date with them.
Identify both the population and the sample.
Population - the responses of all U.S. adults
Sample - the responses of the 23,503 U.S. adults used in the survey
The students receiving bachelor of science degrees from a university include 52 biology majors.
Does the number describe a parameter or a statistic? Explain why.
Parameter
The value of 52 biology majors is a numerical description of all students receiving bachelor of science degrees from a university
Identify the sampling technique used.
Twenty-five students are randomly selected from each grade level at a high school and surveyed about their study habits.
Stratified Sampling
Determine whether the study is an observational study or an experiment. Explain.
Researchers conduct a study to compare attitudes of first and last year medical students toward mental illness. To perform the study, researchers surveyed 111 first and last year students from the Faculty of Medicine of the University of Porto, Portugal.
Observational Study
The study does not attempt to influence the responses of the subjects and there is no treatment
What is the type of statistics that involves using a sample to draw conclusions about a population.
Inferential Statistics
A survey of 1508 U.S. adults ages 40-64 found that 32% had provided regular support to their parents in the past year.
Identify the population and the sample.
Population - the responses of all U.S. adults
Sample - the responses of the 1508 U.S. adults in the survey
In a recent year, the average evidence-based reading and writing score on the SAT was 528.
Does the number describe a parameter or a statistic? Explain why.
Parameter
The average evidence-based reading and writing score of 528 is a numerical description of all test takers in a recent year
Identify the sampling technique used.
A student asks 18 friends to participate in a psychology experiment.
Convenience Sampling
Using a calculator, generate a list of 7 random numbers within the range 1 - 200.
Answers will vary.