Statistical theory

1. Statistical theory is a branch of mathematics that deals with the analysis, interpretation, and presentation of data. It involves various techniques and methods for summarizing and making inferences about a population based on sample data. Key concepts in statistical theory include probability distributions, hypothesis testing, regression analysis, and more. The goal of statistical theory is to provide a framework for understanding uncertainty and variability in data, enabling us to draw meaningful conclusions and make informed decisions in various fields such as science, business, and social sciences.

What is the purpose of hypothesis testing in statistics?

A) To summarize data using summary statistics.
B) To visualize data using graphs.
C) To calculate the probability of an event.
D) To determine if there is enough evidence to reject a null hypothesis.

2. What is the Central Limit Theorem?

A) A method for outlier detection in data.
B) States that the sampling distribution of the sample means approaches a normal distribution as the sample size increases.
C) Describes the spread of data points in a dataset.
D) A type of statistical hypothesis testing.

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

A) When the null hypothesis is not rejected, but it is false.
B) When the null hypothesis is rejected, but it is actually true.
C) A calculation error in statistical analysis.
D) A type of data transformation.

4. What is a Type II error in hypothesis testing?

A) When the null hypothesis is rejected, and it is true.
B) A statistical measure of association.
C) A type of sampling technique.
D) When the null hypothesis is not rejected, but it is actually false.

5. What is correlation in statistics?

A) A measure of the strength and direction of a linear relationship between two variables.
B) A type of data visualization technique.
C) The difference between the maximum and minimum values in a dataset.
D) The probability of an event occurring.

6. What is regression analysis used for in statistics?

A) To determine the mode of a distribution.
B) To analyze the relationship between a dependent variable and one or more independent variables.
C) To calculate the median value of a dataset.
D) To summarize data using descriptive statistics.

7. What is the formula for variance in statistics?

A) The middle value in a set of ordered data points.
B) The range of values in a dataset.
C) The average of the squared differences from the mean.
D) The sum of all data values divided by the number of values.

8. Which of the following is a measure of central tendency?

A) Standard Deviation
B) Correlation Coefficient
C) Mean
D) Variance

9. What is the mode of a dataset?

A) The difference between the maximum and minimum values.
B) The middle value in a sorted dataset.
C) The average of all values in the dataset.
D) The value that appears most frequently in the dataset.

10. What is the range of a dataset?

A) The average of all values in the dataset.
B) The difference between the maximum and minimum values in the dataset.
C) The sum of all values in the dataset.
D) The number of values in the dataset.

11. In a normal distribution, what percentage of data points fall within one standard deviation of the mean?

A) 95%
B) 99.7%
C) 50%
D) 68%

12. What is the standard deviation?

A) The average of all values in the dataset.
B) A measure of the dispersion of data points around the mean.
C) The maximum value in the dataset.
D) The middle value in a sorted dataset.

13. What does skewness measure in a dataset?

A) The presence of outliers in the dataset.
B) The relationship between two variables.
C) The spread of data points from the mean.
D) The degree of asymmetry in the distribution of data.

14. What is the null hypothesis in hypothesis testing?

A) A statement that a significant difference exists between variables.
B) A conclusion drawn from statistical analysis.
C) A statement that there is no significant difference or relationship between variables.
D) A measure of the strength of a relationship.

15. What is a chi-square test used for in statistics?

A) To calculate the correlation coefficient.
B) To analyze the relationship between a dependent and an independent variable.
C) To find the median value of a dataset.
D) To determine if there is a significant association between two categorical variables.

16. What is probability sampling?

A) A sampling technique that selects individuals based on convenience.
B) A sampling technique that relies on random selection of individuals.
C) A non-statistical method of gathering data.
D) A sampling technique where each member of the population has a known and non-zero chance of being selected into the sample.

17. What is a box plot used for in statistics?

A) To calculate confidence intervals.
B) To calculate the average value of a dataset.
C) To visualize the distribution of a dataset and identify outliers.
D) To test for correlations between variables.

18. What is a percentile in statistics?

A) The range of values in a dataset.
B) A value below which a given percentage of observations in a group falls.
C) The variance of a dataset.
D) The average of all data points in a dataset.

19. What is statistical power in hypothesis testing?

A) The significance level for hypothesis testing.
B) The confidence interval for a parameter estimate.
C) The strength of the relationship between variables.
D) The probability of rejecting a false null hypothesis.

20. Which statistical test is used to determine if there is a significant difference between the means of two groups?

A) ANOVA
B) T-test
C) Regression analysis
D) Chi-square test

21. Which of the following is a non-parametric statistical test?

A) Regression analysis
B) T-test
C) Mann-Whitney U test
D) ANOVA

22. What term is used to describe the measure of the spread of values in a dataset?

A) Mean
B) Mode
C) Variance
D) Median

23. Which statistical test is used to compare the means of more than two groups?

A) Chi-square test
B) t-test
C) Regression analysis
D) ANOVA

24. Which distribution is used to model the number of successes in a fixed number of Bernoulli trials?

A) Poisson
B) Binomial
C) Normal
D) Exponential

25. Which type of bias occurs when some groups in a population are systematically left out of a study?

A) Measurement bias
B) Response bias
C) Selection bias
D) Sampling bias

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