Q.1 Which measure of central tendency is most affected by extreme values in a dataset?
Mean
Median
Mode
Range
Explanation - The mean is calculated by summing all values and dividing by the number of values, so extreme values (outliers) can heavily influence it, unlike the median or mode.
Correct answer is: Mean
Q.2 What type of variable is a 'rating of satisfaction' on a scale from 1 to 5?
Nominal
Ordinal
Interval
Ratio
Explanation - Ratings like 1 to 5 indicate order but not necessarily equal intervals between points, making it an ordinal variable.
Correct answer is: Ordinal
Q.3 If the correlation coefficient between two variables is -0.85, what does it indicate?
Strong positive correlation
Weak positive correlation
Strong negative correlation
No correlation
Explanation - A correlation of -0.85 shows a strong negative relationship; as one variable increases, the other decreases.
Correct answer is: Strong negative correlation
Q.4 Which statistical test is appropriate for comparing means of two independent groups?
Paired t-test
Independent t-test
Chi-square test
ANOVA
Explanation - An independent t-test compares the means of two separate groups to determine if the difference is statistically significant.
Correct answer is: Independent t-test
Q.5 What does a p-value less than 0.05 indicate in hypothesis testing?
Accept null hypothesis
Reject null hypothesis
Data is invalid
Population is normally distributed
Explanation - A p-value < 0.05 suggests that the observed effect is statistically significant, leading to rejection of the null hypothesis.
Correct answer is: Reject null hypothesis
Q.6 Which of the following represents a measure of dispersion?
Mean
Median
Standard deviation
Mode
Explanation - Standard deviation quantifies the amount of variability or spread in a dataset, unlike central tendency measures.
Correct answer is: Standard deviation
Q.7 A histogram is used primarily to visualize:
Relationships between two variables
Distribution of a single variable
Proportions of categories
Changes over time
Explanation - Histograms show how values of a single variable are distributed across intervals or bins.
Correct answer is: Distribution of a single variable
Q.8 What is the range of a dataset if the maximum value is 95 and the minimum is 50?
45
50
95
145
Explanation - Range = Maximum - Minimum = 95 - 50 = 45.
Correct answer is: 45
Q.9 Which type of sampling involves every member of the population having an equal chance of being selected?
Convenience sampling
Snowball sampling
Simple random sampling
Quota sampling
Explanation - In simple random sampling, each member of the population has an equal probability of selection, minimizing selection bias.
Correct answer is: Simple random sampling
Q.10 Which statistical test is suitable for examining the association between two categorical variables?
Independent t-test
Chi-square test
ANOVA
Correlation coefficient
Explanation - Chi-square tests assess whether there is a significant association between two categorical variables.
Correct answer is: Chi-square test
Q.11 In a normal distribution, approximately what percentage of values lie within one standard deviation of the mean?
50%
68%
95%
99%
Explanation - According to the empirical rule, about 68% of values in a normal distribution lie within ±1 standard deviation from the mean.
Correct answer is: 68%
Q.12 What is the primary purpose of inferential statistics?
Describe a sample
Visualize data
Make predictions about a population
Calculate central tendency
Explanation - Inferential statistics allow researchers to draw conclusions and make predictions about a population based on sample data.
Correct answer is: Make predictions about a population
Q.13 Which of the following is NOT an assumption of parametric tests?
Normal distribution
Homogeneity of variance
Interval or ratio scale
Random sampling is optional
Explanation - Parametric tests assume normality, equal variances, and interval/ratio data, and require random sampling to generalize results.
Correct answer is: Random sampling is optional
Q.14 What does the coefficient of determination (R²) indicate?
Strength and direction of relationship
Proportion of variance explained by the model
Mean difference between groups
Sample size adequacy
Explanation - R² shows the proportion of the dependent variable's variance explained by the independent variable(s) in a regression model.
Correct answer is: Proportion of variance explained by the model
Q.15 Which plot is best for visualizing the relationship between two continuous variables?
Bar chart
Scatter plot
Histogram
Pie chart
Explanation - Scatter plots show individual data points and help identify correlations, trends, or clusters between two continuous variables.
Correct answer is: Scatter plot
Q.16 If a dataset is skewed to the right, which measure of central tendency is typically the largest?
Mean
Median
Mode
Range
Explanation - Right-skewed distributions have long tails on the right; extreme high values pull the mean above the median and mode.
Correct answer is: Mean
Q.17 Which of the following is a non-parametric test?
Independent t-test
Paired t-test
Mann-Whitney U test
ANOVA
Explanation - Mann-Whitney U is a non-parametric alternative to the independent t-test, used when assumptions of normality are violated.
Correct answer is: Mann-Whitney U test
Q.18 What is the standard error of the mean?
Population standard deviation
Standard deviation of sample means
Difference between sample and population mean
Variance of the population
Explanation - The standard error measures the variability of sample means around the population mean, reflecting the precision of the sample estimate.
Correct answer is: Standard deviation of sample means
Q.19 A researcher wants to compare means of three or more groups. Which test should be used?
Independent t-test
Paired t-test
ANOVA
Chi-square test
Explanation - ANOVA (Analysis of Variance) is used to compare the means of three or more groups to see if at least one group differs significantly.
Correct answer is: ANOVA
Q.20 What is a Type I error in hypothesis testing?
Failing to reject a false null hypothesis
Rejecting a true null hypothesis
Accepting a false alternative hypothesis
Rejecting a false alternative hypothesis
Explanation - A Type I error occurs when we incorrectly reject the null hypothesis even though it is actually true.
Correct answer is: Rejecting a true null hypothesis
Q.21 Which of the following is used to measure internal consistency of a scale?
Cronbach's alpha
Pearson correlation
Chi-square test
ANOVA
Explanation - Cronbach's alpha assesses how closely related a set of items are as a group, indicating the reliability of a scale.
Correct answer is: Cronbach's alpha
Q.22 What does it mean if two variables are independent?
One variable causes the other
They have a correlation of 1
The value of one variable does not affect the other
They have a negative correlation
Explanation - Independence between variables means the outcome or value of one variable provides no information about the other variable.
Correct answer is: The value of one variable does not affect the other
Q.23 Which measure is most appropriate for describing the spread of a nominal variable?
Range
Variance
Mode
Standard deviation
Explanation - For nominal variables, only the mode is meaningful since nominal data are categorical and have no numeric spread.
Correct answer is: Mode
Q.24 What is the purpose of a confidence interval?
To estimate the population mean with a degree of certainty
To calculate correlation
To test categorical associations
To visualize data distribution
Explanation - A confidence interval gives a range of plausible values for a population parameter, reflecting the uncertainty of the estimate.
Correct answer is: To estimate the population mean with a degree of certainty