3.7 Scope of Inference

What is a key requirement for statistical inference to be valid?

• The sample must be large.

• The sample must be selected randomly from the population.

• The data must be collected through an observational study.

• The results must show a strong association.

What is the main limitation when volunteers are used in an experiment?

• The experiment cannot show any relationships between variables.

• The results can only be generalized to the volunteers themselves.

• It becomes impossible to randomly assign subjects to treatment groups.

• The experiment will always have confounding variables.

What is essential for an experimental study to establish a cause and effect relationship?

• A large sample size.

• Random assignment of subjects to treatment groups.

• The use of volunteers.

• Observing existing relationships without intervention.

In a perfect experiment, what two conditions must be met to conclude that an explanatory variable causes a change in the response variable for all people in the population?

• Random selection of subjects and a large sample size.

• Random assignment of subjects to treatment groups and a small sample size.

• Random selection of subjects from the population and random assignment to treatment groups.

• The use of volunteers and observation of existing relationships.

Are you enjoying the video lesson?

• Yes

• No

What is NOT sufficient on its own to determine if a difference between statistics is statistically significant?

• Observing a large numerical difference between the statistics.

• Having at least two treatment groups in the experiment.

• Calculating the average scores for each group.

• Knowing the number of participants in each group.

What is the primary job of statisticians hired by researchers in an experiment?

• To collect all the data from the treatment groups.

• To design the experiment and select participants.

• To determine if the observed differences between statistics are statistically significant.

• To interpret the results and write the final report.

What does it mean if the difference between two or more statistics is deemed statistically significant?

• The difference occurred purely by chance.

• The difference was too large to have occurred by chance.

• The difference is exactly 10% or more.

• The difference is due to measurement error.

When a difference is observed between two statistics in an experiment, what are the two main possibilities regarding its cause?

• The difference is due to human error or equipment malfunction.

• The difference occurred by chance, or it's due to the explanatory variable directly causing the response variable to change.

• The difference is either statistically significant or not statistically significant.

• The difference is caused by external factors or internal biases.

Some news organizations maintain a database of customers who have volunteered to share their opinions on a variety of issues. Suppose that one of these databases includes 9000 registered voters in california. To measure the amount of support for a controversial ballot issue, 1000 registered voters in California are randomly selected from the database and asked their opinion. Which of the following is the largest population to which the results of this survey should be generalized?

• The 1000 people in the sample.

• The 9000 registered voters from California in the database

• All registered voters in California

• All registered voters in the United States