FREE Data Science Statistical Concepts and Analysis Questions and Answers

Question 1

A data scientist runs an A/B test on a new website feature and calculates a p-value of 0.03.
The significance level (alpha) was set at 0.05.
Which of the following is the most accurate interpretation of this result?

Accepted Answer

The result is statistically significant, providing evidence to reject the null hypothesis.

Answer

There is a 3% probability that the new feature has no effect on the outcome.

Answer

The result is not statistically significant, so the null hypothesis cannot be rejected.

Answer

There is a 97% probability that the new feature is effective.

Question 2

In the context of the bias-variance tradeoff in machine learning, a model with high variance and low bias is most likely to exhibit which of the following?

Accepted Answer

Overfitting, where it performs very well on training data but poorly on test data.

Answer

Underfitting, where it performs poorly on both training and test data.

Answer

A good balance, leading to optimal performance on unseen data.

Answer

High error on training data and low error on test data.

Question 3

A pharmaceutical company is testing a new drug. The null hypothesis is that the drug has no effect. A Type I error in this scenario would be:

Accepted Answer

Concluding the drug is effective when it actually is not.

Answer

Concluding the drug has no effect when it actually is effective.

Answer

Correctly concluding the drug is effective.

Answer

Correctly concluding the drug has no effect.

Question 4

A pollster wants to estimate the average income of adults in a large city. They take a random sample of 500 adults. According to the Central Limit Theorem, what can be said about the distribution of the sample mean income?

Accepted Answer

It will be approximately a normal distribution, regardless of the city's actual income distribution.

Answer

It will have the same distribution as the city's overall income distribution.

Answer

It will be a uniform distribution because the sample is random.

Answer

Its distribution cannot be determined without knowing the population's distribution.

Question 5

A data analyst calculates a 95% confidence interval for the average user engagement time on a new app feature to be [15.2 minutes, 18.6 minutes]. What is the correct interpretation of this interval?

Accepted Answer

If we were to repeat this sampling process many times, 95% of the calculated confidence intervals would contain the true average engagement time for all users.

Answer

95% of all users have an engagement time between 15.2 and 18.6 minutes.

Answer

There is a 95% probability that the average engagement time for all users is between 15.2 and 18.6 minutes.

Answer

The average engagement time for the users in the sample was exactly in the middle of this interval.

Question 6

In an A/B test comparing two website designs (A and B), the goal is to determine which design leads to a higher conversion rate. What is the primary purpose of determining statistical significance in this context?

Accepted Answer

To ensure the observed difference between the designs is due to their effectiveness and not random chance.

Answer

To guarantee that the winning design will perform better in the future.

Answer

To measure the exact percentage increase in conversion rate.

Answer

To decide how large the sample size for the test should be.

A data scientist runs an A/B test on a new website feature and calculates a p-value of 0.03.The significance level (alpha) was set at 0.05.Which of the following is the most accurate interpretation of this result?

A data scientist runs an A/B test on a new website feature and calculates a p-value of 0.03.
The significance level (alpha) was set at 0.05.
Which of the following is the most accurate interpretation of this result?