Compare queues and interpret distributions
Company: LinkedIn
Role: Data Scientist
Category: Statistics & Math
Difficulty: medium
Interview Round: Technical Screen
You are asked several conceptual statistics questions:
1. Two banks each have 5 tellers. Bank A uses one common queue feeding all 5 tellers. Bank B uses 5 separate queues, one per teller. Assume tellers are equally skilled, customers are served first-come-first-served, and arrival/service rates are otherwise similar. Which system would you rather join, and why?
2. Sketch and describe the distribution of adult male heights in the United States, adult female heights in the United States, and the combined distribution when both groups are pooled together.
3. On a social network such as LinkedIn, sketch the distribution of users' number of connections. Is it symmetric, left-skewed, or right-skewed? For that distribution, compare the mean, median, and mode, and explain why.
4. Are L1-regularized (lasso) and L2-regularized (ridge) estimators unbiased? Why or why not?
Quick Answer: This question evaluates understanding of queueing theory and service systems, interpretation and visualization of univariate distributions and skewness, comparison of mean/median/mode, and properties of L1 versus L2 regularized estimators.