Understanding Statistical Analysis

Which statement about statistical analysis is false?

• Experiments can suggest patterns and relationships in data.

• Experiments can determine cause and effect relationships.

• Observational studies can determine cause and effect relationships.

• Observational studies can suggest patterns and relationships in data.

Answer explanation

Observational studies cannot determine cause and effect relationships, only suggest patterns and relationships in data.

Which investigation technique is most often used to determine if a single variable has an impact on a given population?

• observational study

• random survey

• controlled experiment

• formal interview

Answer explanation

A controlled experiment is the most often used investigation technique to determine if a single variable has an impact on a given population by manipulating the variable and observing the outcomes.

A researcher randomly divides 50 bean plants into two groups. He puts one group by a window to receive natural light and the second group under artificial light. He records the growth of the plants weekly. Which data collection method is described in this situation?

• observational study

• controlled experiment

• survey

• systematic sample

Answer explanation

The described situation involves dividing plants into groups to compare growth under different conditions, which aligns with a controlled experiment where variables are controlled and manipulated to observe outcomes.

A sociologist reviews randomly selected surveillance videos from a public park over a period of several years and records the amount of time people spent on a smartphone. The statistical procedure the sociologist used is called

• a census

• an experiment

• an observational study

• a sample survey

Answer explanation

The correct choice is an observational study because the sociologist observed and recorded behavior without intervening or manipulating variables.

A veterinary pharmaceutical company plans to test a new drug to treat a common intestinal infection among puppies. The puppies are randomly assigned to two groups. Half of the puppies will receive the drug, and the other half will receive a placebo. The veterinarians monitor the puppies. This is an example of which study method?

• census

• observational study

• survey

• controlled experiment

Answer explanation

This is a controlled experiment because the puppies are randomly assigned to receive either the drug or a placebo, allowing for a comparison of the effects of the drug.

A researcher wants to determine if room-darkening shades cause people to sleep longer. Which method of data collection is most appropriate?

• census

• survey

• observational study

• controlled experiment

Answer explanation

A controlled experiment is the most appropriate method to determine causation between room-darkening shades and sleep duration by manipulating variables in a controlled setting.

A cafeteria food manager studied the lunchtime eating habits of a group of employees in their office building. The purpose of the study was to determine the proportion of employees who purchased lunch in the cafeteria, brought their lunch from home, or purchased lunch from an outside vendor. This collection of data would best be classified as

• a census

• an experimental

• an observational study

• a simulation

Answer explanation

The data collection of studying lunchtime eating habits of employees in an office building is best classified as a census because it aims to gather information from the entire population rather than a sample.

In watching auditions for lead singer in a band, Liem became curious as to whether there is an association between how animated the lead singer is and the amount of applause from the audience. He decided to watch each singer and rate the singer on a scale of 1 to 5, where 1 is the least animated and 5 is the most animated. He did this for all 5 nights of auditions and found that the more animated singers did receive louder applause. The study Liem conducted would be best described as

• experimental

• observational

• a sample survey

• a random assignment

Answer explanation

The study conducted by Liem is best described as observational because he observed and rated the singers without manipulating any variables.

Which scenario is best described as an observational study?

• A class project where students in Health class ask every tenth student entering the school if they eat breakfast in the morning.

• A social researcher determining whether there is a link between school attendance and grades by gathering data from 15 school districts.

• A researcher studying the link between children's daily activity and their overall energy level by observing them during lunch at the local high school.

• A class in Advanced Algebra Concepts where students are randomly divided into two groups, one using calculators all the time and the other not.

Answer explanation

The best scenario described as an observational study is the researcher studying the link between children's daily activity and their overall energy level by observing them during lunch at the local high school.

Which method of data collection is most likely to result in a biased sample when trying to estimate the proportion of all registered voters in a district that support improvements to the high school football field?

• At a football game

• At a supermarket

• At a school fund-raiser

• At a high school band concert

Answer explanation

At a football game is most likely to result in a biased sample as attendees may have a higher interest in football-related topics, skewing the results.