# Errata for "Performance Modeling and Design of Computer Systems"

• p. 36. Bayes Law and Extended Bayes Law should both include the words: Assuming P{E}> 0.
• p. 47. In the expression for \var(X), the term involving an integral should use little x not big X.
• p. 49. Def 3.21. Replace "Let A be an event" with "Let A be an event s.t. P{A} > 0."
• p. 61. Thm 3.33 Replace "variance" by "finite variance."
• p. 65. Exercise 3.4. Replace "each with positive probability" with "each with positive probability and with non-zero intersection."
• p. 65. Exercise 3.8(a). Replace "Which has lower variance" with "Which is lower?"
• p. 105. 2nd line: 0.775 * 40 should be 0.0775 * 40.
• p. 119. In the text, N = 20 should be replaced with N=10, so that it matched the figure.
• p. 120. Remove the entire line: T=650 seconds (the length of the observation interval).
• p. 124. Exercise 7.4. Remove the entire line: "Observation interval = 17 minutes."
• p. 143. The following sentence is missing: "Specifically, a packet can "arrive" and "depart" within the same time step, leaving the system in the same state." This sentence should be placed just after the sentence: "Note that during a time step, we might have both an arrival and a transmission, or neither."
• p. 152. non-negative coefficients --> non-negative integer coefficients
• p. 153. The \vec{e} in the first displayed math line shouldn't be there.
• p. 185. Exercise 9.8. w_{ij} = w_{ji} > 0, forall i,j.
• p. 222. Exercise 11.4. The density function is defined for t \geq 0.
• p. 358. Exercise 20.2 -- Taile => Tailed
• p. 436-437. In taking the nth derivative, must write ds^n. Likewise for kth derivative ds^k, and for 2nd derivative ds^2.
• p. 446. Exercise 25.6. Assume that the Poisson process has rate \lambda.
• p. 446. Exercise 25.7. X is non-negative and continuous.
• p. 501. The formula for E[S_e] should be E[S^2]/(2 E[S]).
• p. 525. Figure 33.2. The x-axis should be labeled 0, 2, 4, 6, 8, 10. The decimals shown there are wrong.

Please send me more errors as you find them: harchol@cs.cmu.edu