1. ECSE-4963: Experimental Networking Exam 1
Time: 60 min (strictly enforced)
Points: 50
YOUR NAME:
Be brief, but DO NOT omit necessary detail
{Note: Simply copying text directly from the slides or notes will not earn (partial) credit. Brief, clear and consistent explanation will.}

2. 1. [12 pts] Given: n=6 random RTT samples (in ms):
{30, 22, 29, 52, 28, 41}
Find: sample mean (xbar), sample standard deviation (s), 90% confidence interval (CI) & 99% CI for the population mean

3. 2. [15 pts] BRIEFLY, what is the difference between:
a) “random variable” vs “event” [2 pts]
b) “joint distribution” vs “marginal distribution” [2 pts]
c) “un-correlated” vs “independent” [2 pts]
d) “mean” vs “median” [2 pts]
e) “standard deviation” vs “SIQR” [2 pts]
Explain succinctly: [5 pts]
i) What is the concept of probability measure, and why you can be deterministic about it when the underlying outcomes are random? [2.5 pts]
ii) What is the idea of a “confidence interval” and why it is worthy of your confidence? [2.5 pts]

6. II. [10 pts] Experiment Design: Analyze the 2^3 design
Quantify all the main effects and all interactions [5 pts]
Quantify percentages of variations explained [3 pts]
Sort the variables in the order of decreasing importance [2 pts] A1 A2 C1 C2 B1
100 25 90 30 B2 40 35

8. [15 pts] DESIGN WALK-THROUGH: We learnt about animation, simulation (ns-2), and graphing tools. Assume that you are given a novel design for TCP that improves its congestion control algorithm by replacing its increase/decrease formula by the new formula:
What issues are important to characterize the performance of this new scheme relative to the earlier version of TCP (that uses AIMD) ? [4 pts]
What are the “parameters” and “metrics” you would use to study if this design “improvement” is indeed a wise one? Argue why your set of metrics and parameters is a complete and meaningful set. [4pts]
Walk me through how you would systematically use the above tools (in the right sequence) to help design and incrementally refine your design. [4 pts]
What set of workloads would you use to test such a system & explain why they are meaningful, and helps you make quick progress in your evaluation process. [3 pts]