MCQs

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Overall MCQs for Reference

What does variance measure in data science?
a. Central tendency
b. Spread of data points
c. Slope of a regression line
d. Sample mean
Answer: b. Spread of data pointsdigitalregenesys+2
What is the formula for variance in a population dataset?
a.
b.
c.
d.
Answer: a. testbook+2
Variance is expressed in which units?
a. Same as the mean
b. Original data units
c. Squared units of the data
d. Percentage
Answer: c. Squared units of the datageeksforgeeks+1
What is the relationship between standard deviation and variance?
a. Variance is the square of the standard deviation
b. Standard deviation is the square of the variance
c. They are always equal
d. They are unrelated
Answer: a. Variance is the square of the standard deviationw3schools+2
What symbol is most commonly used to denote variance?
a.
b.
c.
d.
Answer: b. geeksforgeeks+1
What happens to variance if every value in the dataset is multiplied by a constant ?
a. Remains unchanged
b. Multiplied by
c. Multiplied by
d. Divided by
Answer: c. Multiplied by testbook+1
For a data series , variance is:
a. 5
b. 25
c. 1
d. 0
Answer: d. 0testbook+1
In a data science context, high variance in data usually signifies:
a. Data points are close together
b. Data points are far from the mean
c. All values are the same
d. Low spread
Answer: b. Data points are far from the meandigitalregenesys+1
Which of the following is not a measure of dispersion?
a. Variance
b. Mean deviation
c. Median
d. Standard deviation
Answer: c. Medianscaffoldingtechnology+1
The average of squared deviations from the mean is called:
a. Standard deviation
b. Quartile deviation
c. Variance
d. None of the above
Answer: c. Variancebyjus+2
Why are squared deviations used in variance?
a. To highlight the mean
b. To eliminate negative signs
c. To make values smaller
d. To standardize data
Answer: b. To eliminate negative signsw3schools+1
The variance for binomial distribution is given by:
a.
b.
c.
d.
Answer: c. testbook
If the variance of a dataset is zero, what does it indicate?
a. All values are identical
b. All values are negative
c. Data is normally distributed
d. High spread
Answer: a. All values are identicaldigitalregenesys+1
For a sample of size , what is the denominator in the unbiased sample variance formula?
a.
b.
c.
d.
Answer: b. scribd+1
What effect does adding a constant to each observation have on the variance?
a. Increases variance
b. Decreases variance
c. No effect
d. Makes it negative
Answer: c. No effectw3schools+1
Which statistical measure represents the spread of data around the mean?
a. Median
b. Mean
c. Mode
d. Variance
Answer: d. Varianceplacementpreparation
Variance is always:
a. Non-negative
b. Negative
c. Zero or negative
d. Randomly signed
Answer: a. Non-negativegeeksforgeeks+1
What is the primary application of variance in data science?
a. Predicting categorical values
b. Measuring dispersion and risk
c. Estimating mode
d. Ranking data
Answer: b. Measuring dispersion and riskroadmap+1
In which scenario is high variance not desirable?
a. Predicting stock prices
b. Analyzing randomized experiments
c. Testing outliers
d. Quality control processes
Answer: d. Quality control processesroadmap+1
The variance of a set of standardized values is always:
a. 0
b. 1
c.
d. Data dependent
Answer: b. 1geeksforgeeks+1
Which is a robust alternative to variance for data with outliers?
a. Median absolute deviation
b. Sample mean
c. Quartile average
d. Mode
Answer: a. Median absolute deviationscaffoldingtechnology
What is the coefficient of variation?
a. Standard deviation divided by mean
b. Mean divided by variance
c. Variance divided by median
d. None of the above
Answer: a. Standard deviation divided by meanscaffoldingtechnology+1
If variance increases, what happens to the standard deviation?
a. Increases
b. Decreases
c. Remains unchanged
d. Unpredictable
Answer: a. Increasestestbook+1
What is the variance for the dataset ?
a. 5
b. 6.67
c. 4
d. 3
Answer: b. 6.67scribd+1
Which scenario results in lower variance?
a. Data tightly clustered around mean
b. Data widely scattered
c. Uniform distribution
d. High outliers
Answer: a. Data tightly clustered around meandigitalregenesys+1
Among the measures below, which uses squared values?
a. Range
b. Mode
c. Variance
d. Median
Answer: c. Variancebyjus+1
What can variance help identify in data science?
a. Outliers
b. Mean
c. Probability density
d. Classification type
Answer: a. Outliersroadmap+1
The sum of deviations from the mean is always:
a. Positive
b. Negative
c. Zero
d. One
Answer: c. Zeroscaffoldingtechnology+1
The notation usually refers to:
a. Population mean
b. Sample variance
c. Population variance
d. Standard deviation
Answer: b. Sample variancew3schools+1
Which framework heavily relies on variance for evaluation?
a. PCA (Principal Component Analysis)
b. Decision trees
c. CNNs
d. Tokenization
Answer: a. PCA (Principal Component Analysis)roadmap+1
High variance in a model may indicate:
a. Overfitting
b. Underfitting
c. Good generalization
d. Low accuracy
Answer: a. Overfittinggithub+1
Which of these statements is true?
a. Variance can be negative
b. Variance has the same unit as data
c. Zero variance means no spread
d. Variance equals absolute deviations
Answer: c. Zero variance means no spreaddigitalregenesys+1
In regression, variance of the residuals measures:
a. Goodness of fit
b. Spread of errors
c. Average value
d. Feature importance
Answer: b. Spread of errorssanfoundry+1
Variance is least impacted by:
a. Outliers
b. Mean
c. Data duplication
d. Number of variables
Answer: c. Data duplicationgeeksforgeeks
What is the variance of a dataset where every value equals the mean?
a. 1
b. Infinite
c. 0
d. Depends on n
Answer: c. 0digitalregenesys+1
How is population variance denoted in statistics?
a.
b.
c.
d.
Answer: b. w3schools+1
Which best describes a low variance dataset?
a. Large deviations from mean
b. Many outliers
c. Values close to mean
d. Bimodal distribution
Answer: c. Values close to meangeeksforgeeks+1
In exploratory data analysis, variance helps to:
a. Summarize the mode
b. Identify data spread
c. Omit missing values
d. Rank categories
Answer: b. Identify data spreadscribd+1
What happens if you square the variance?
a. Standard deviation
b. Same value
c. Fourth-moment
d. Variance remains unchanged
Answer: c. Fourth-momentw3schools+1
For normally distributed data, about 68% falls within how many standard deviations of the mean?
a. 1
b. 2
c. 3
d. 4
Answer: a. 1scaffoldingtechnology+1
Which is not true regarding variance?
a. Can be negative
b. Non-negative
c. Indicates spread
d. Based on squared deviations
Answer: a. Can be negativedigitalregenesys+1
In machine learning, low variance often leads to:
a. Underfitting
b. Overfitting
c. High predictive risk
d. Poor scaling
Answer: a. Underfittingdevinterview+1
The variance of a binary variable with probabilities p and q is:
a.
b.
c.
d.
Answer: a. testbook
What is the effect of combining two identical datasets on variance?
a. Halved
b. Doubled
c. Unchanged
d. Random
Answer: c. Unchangedgeeksforgeeks+1
In which of the following is variance least meaningful?
a. Continuous data
b. Nominal data
c. Interval data
d. Ratio data
Answer: b. Nominal datadigitalregenesys
Variance in data science aids in:
a. Data scaling
b. Model selection
c. Outlier detection
d. All of the above
Answer: d. All of the abovegeeksforgeeks+1
How does variance relate to risk in financial data science?
a. Lower variance = higher risk
b. Higher variance = higher risk
c. No relationship
d. Indirect relationship
Answer: b. Higher variance = higher riskroadmap+1
Which of the following best estimates sample variance?
a. Divide sum by n
b. Divide sum by n-1
c. Add all values
d. Take square root
Answer: b. Divide sum by n-1scribd+1
Which statement about variance is false?
a. It is always zero or positive
b. It is affected by extreme values
c. Calculated with squared deviations
d. Larger variance means tighter data clustering
Answer: d. Larger variance means tighter data clusteringdigitalregenesys+1
When is variance maximized for a set of numbers with a fixed sum?
a. When all values are equal
b. When values are as far apart as possible
c. When mean equals zero
d. When values are positive
Answer: b. When values are as far apart as possiblegeeksforgeeks+1

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