Đề thi, bài tập trắc nghiệm online Lý thuyết xác suất và thống kê – Đề 6

1. What is the purpose of calculating correlation?

A. To determine causality between variables.

B. To measure the strength and direction of a linear relationship between two quantitative variables.

C. To compare means of different groups.

D. To predict future values of a variable with certainty.

2. What is the purpose of data visualization in statistics?

A. To make data analysis more complicated.

B. To replace statistical analysis.

C. To communicate data patterns, insights, and findings effectively and understandably.

D. To hide outliers in data.

3. What is the difference between descriptive and inferential statistics?

A. Descriptive statistics are used for populations, while inferential statistics are used for samples.

B. Descriptive statistics summarize and describe data, while inferential statistics use sample data to make generalizations or inferences about a population.

C. Descriptive statistics are more complex than inferential statistics.

D. There is no difference; they are the same thing.

4. What is the purpose of a confidence interval?

A. To estimate the probability of a specific event occurring.

B. To provide a range of plausible values for a population parameter based on sample data.

C. To determine the exact value of a population parameter.

D. To test the hypothesis that the sample mean is equal to the population mean.

5. Which type of statistical test is used to compare the means of two independent groups?

A. Chi-squared test

B. Correlation test

C. T-test

D. ANOVA

6. In hypothesis testing, what does the p-value represent?

A. The probability that the null hypothesis is true.

B. The probability of rejecting the null hypothesis when it is actually true.

C. The probability of observing the data (or more extreme data) if the null hypothesis were true.

D. The probability of accepting the null hypothesis when it is false.

7. What does the term 'variance' measure in statistics?

A. The central tendency of a dataset.

B. The average squared deviation from the mean, indicating the spread of data points around the mean.

C. The frequency of the most common value in a dataset.

D. The difference between the maximum and minimum values in a dataset.

8. In probability, what is the sum of probabilities of all possible outcomes in a sample space?

A. 0

B. 0.5

C. 1

D. Infinity

9. What is the relationship between standard deviation and variance?

A. Variance is the square root of the standard deviation.

B. Standard deviation is the square root of the variance.

C. They measure different aspects of data dispersion.

D. They are the same thing, just different terms.

10. What is a Type I error in hypothesis testing?

A. Failing to reject a false null hypothesis.

B. Correctly rejecting a false null hypothesis.

C. Rejecting a true null hypothesis.

D. Correctly failing to reject a true null hypothesis.

11. What is the role of randomization in experimental design?

A. To make the experiment more complex.

B. To introduce bias into the study.

C. To ensure that treatment groups are as similar as possible at the start of the experiment, reducing the influence of confounding variables.

D. To make data analysis easier.

12. Which type of data is considered qualitative?

A. Height in centimeters

B. Temperature in degrees Celsius

C. Eye color

D. Weight in kilograms

13. Which of the following is NOT a property of the normal distribution?

A. Symmetric around the mean.

B. Unimodal (has one mode).

C. Skewed to the right.

D. Bell-shaped.

14. Which of the following statements is TRUE regarding the relationship between sample size and margin of error?

A. As sample size increases, margin of error increases.

B. As sample size decreases, margin of error decreases.

C. As sample size increases, margin of error decreases.

D. Sample size and margin of error are unrelated.

15. Which of the following scenarios best illustrates the concept of conditional probability?

A. Rolling a fair die and getting a 6.

B. Drawing a red card from a standard deck of cards.

C. The probability of rain tomorrow, given that it is cloudy today.

D. The probability of winning the lottery.

16. What is the purpose of factor analysis?

A. To predict future outcomes based on past data.

B. To reduce the dimensionality of data by identifying underlying factors that explain the correlations among a set of observed variables.

C. To compare means of different groups.

D. To test hypotheses about population parameters.

17. What is the difference between a population and a sample?

A. A population is always larger than a sample.

B. A population is the entire group of individuals we are interested in studying, while a sample is a subset of the population.

C. A sample is more reliable than a population for statistical analysis.

D. There is no difference; the terms are interchangeable.

18. What is the significance of the Central Limit Theorem in statistics?

A. It states that the probability of any event is between 0 and 1.

B. It describes the distribution of sample means approaching a normal distribution as the sample size increases, regardless of the population distribution.

C. It is used to calculate the probability of rare events.

D. It defines the relationship between variance and standard deviation.

19. What is the purpose of resampling techniques like bootstrapping?

A. To reduce the sample size.

B. To estimate the sampling distribution of a statistic and assess its variability when analytical solutions are complex or unavailable.

C. To make data analysis faster.

D. To replace traditional statistical methods.

20. What is the fundamental difference between probability and statistics?

A. Probability deals with past events, while statistics deals with future events.

B. Probability predicts the likelihood of future events based on known parameters, while statistics infers parameters from observed data.

C. Probability is used for small datasets, while statistics is used for large datasets.

D. Probability is a branch of mathematics, while statistics is a branch of computer science.

21. In Bayesian statistics, what is the 'prior probability'?

A. The probability calculated after observing the data.

B. The probability of the data given the hypothesis.

C. The initial belief or probability of a hypothesis before observing any data.

D. The probability of rejecting the null hypothesis.

22. Which of the following is a potential source of bias in statistical studies?

A. Large sample size

B. Random sampling

C. Non-response bias

D. Double-blind design

23. Which of the following is an example of a sampling method that is NOT a probability sampling method?

A. Simple random sampling

B. Stratified sampling

C. Cluster sampling

D. Convenience sampling

24. Which of the following probability distributions is best suited for modeling the number of successes in a fixed number of independent trials?

A. Normal distribution

B. Poisson distribution

C. Binomial distribution

D. Exponential distribution

25. What is the difference between discrete and continuous random variables?

A. Discrete variables can take any value, while continuous variables can only take integer values.

B. Discrete variables can only take integer values or countable values, while continuous variables can take any value within a range.

C. Discrete variables are always positive, while continuous variables can be negative.

D. There is no difference between them.

26. In statistics, what is meant by 'statistical significance'?

A. The practical importance of the results.

B. The certainty that the results are absolutely true.

C. The likelihood that the observed effect is not due to random chance alone, based on a chosen significance level.

D. The size of the sample used in the study.

27. Which of the following is NOT a measure of dispersion?

A. Variance

B. Standard Deviation

C. Median

D. Range

28. Which of the following is a potential disadvantage of using the mean as a measure of central tendency?

A. It is always difficult to calculate.

B. It is not affected by extreme values (outliers).

C. It is sensitive to extreme values (outliers).

D. It cannot be used with continuous data.

29. What is the meaning of 'degrees of freedom' in statistical tests?

A. The number of data points in a dataset.

B. The number of independent pieces of information available to estimate a parameter.

C. The level of confidence in a statistical test.

D. The probability of making a Type I error.

30. What is the purpose of regression analysis?

A. To summarize data using descriptive statistics.

B. To test hypotheses about population parameters.

C. To model the relationship between a dependent variable and one or more independent variables.

D. To calculate probabilities of events.