CBDA Statistical Analysis & Methods 2 — Questions and Answers
Question 1: Which sampling method ensures that every member of the population has an equal chance of being selected?
- Convenience sampling
- Simple random sampling (Correct answer)
- Quota sampling
- Purposive sampling
Correct answer: Simple random sampling
Simple random sampling gives every individual in the population an equal and independent chance of being included.
Question 2: A CBDA analyst wants to compare average customer satisfaction scores across three or more business regions. Which statistical test is MOST appropriate?
- Paired t-test
- One-way ANOVA (Correct answer)
- Chi-square test
- Pearson correlation
Correct answer: One-way ANOVA
One-way ANOVA tests whether mean scores differ significantly across three or more independent groups.
Question 3: What is 'multicollinearity' and why is it a concern in multiple regression analysis for business analysts?
- When the dependent variable has multiple modes
- When independent variables are highly correlated with each other, inflating coefficient estimates (Correct answer)
- When residuals are not normally distributed
- When the sample size is smaller than the number of predictors
Correct answer: When independent variables are highly correlated with each other, inflating coefficient estimates
Multicollinearity makes it difficult to isolate the individual effect of each predictor, reducing model interpretability.
Question 4: In descriptive statistics, what does the interquartile range (IQR) measure?
- The difference between the mean and median
- The spread of the middle 50% of data values (Correct answer)
- The variance of the entire dataset
- The range between the minimum and maximum values
Correct answer: The spread of the middle 50% of data values
The IQR is Q3 minus Q1 and captures the spread of the central half of the data, resistant to outlier influence.
Question 5: A business analyst uses stratified random sampling when analyzing customer data. What is the PRIMARY advantage of this approach?
- It is faster and cheaper than simple random sampling
- It ensures proportional representation of key subgroups in the sample (Correct answer)
- It eliminates the need for a sampling frame
- It guarantees a larger sample size
Correct answer: It ensures proportional representation of key subgroups in the sample
Stratified sampling divides the population into subgroups (strata) and samples from each, ensuring all key segments are represented.
Question 6: Pearson correlation coefficient (r) ranges from -1 to +1. What does a value of -0.85 indicate?
- A weak positive linear relationship
- A strong negative linear relationship (Correct answer)
- No relationship between the two variables
- A non-linear relationship
Correct answer: A strong negative linear relationship
A value of -0.85 indicates a strong negative linear relationship: as one variable increases, the other decreases substantially.
CBDA Statistical Analysis & Methods 2
Which sampling method ensures that every member of the population has an equal chance of being selected?