Statistics Questions et reponses d'entretien
Question 21. What is the coefficient of determination (R-squared) in regression analysis?
The coefficient of determination, denoted as R-squared, measures the proportion of the variance in the dependent variable that is predictable from the independent variables. It ranges from 0 to 1.
Example:
If R-squared is 0.75, 75% of the variance in the dependent variable is explained by the independent variables.
Question 22. Define skewness in statistics.
Skewness measures the asymmetry of the probability distribution of a real-valued random variable. A negative skewness indicates a distribution that is skewed to the left, and a positive skewness indicates a distribution that is skewed to the right.
Example:
A dataset with a long tail to the right has positive skewness.
Question 23. What is the purpose of a t-test?
A t-test is used to determine if there is a significant difference between the means of two groups. It is often applied when the sample size is small and the population standard deviation is unknown.
Example:
Comparing the average scores of two groups of students who were taught using different methods.
Question 24. Define outlier in the context of statistical analysis.
An outlier is an observation that lies an abnormal distance from other values in a random sample from a population. It may indicate a data entry error, measurement error, or a rare event.
Example:
In a dataset of exam scores, a score of 120 when others range from 50 to 100 may be an outlier.
Question 25. What is the purpose of a box plot (box-and-whisker plot)?
A box plot is used to display the distribution and spread of a dataset. It shows the median, quartiles, and potential outliers in a compact visual format.
Example:
Comparing the distribution of salaries in different departments using box plots.
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