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This Defense Intelligence Agency reference document, dated 11 March 2010, is one of the advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) program. It introduces the Statistical Drake Equation, which replaces each factor of Frank Drake's 1961 equation with a uniform random variable to estimate how far away the nearest extraterrestrial civilization is. In the worked example, there is a 75% probability that the nearest civilization lies between 1,361 and 3,979 light years from Earth.
“Works”7 pages
UNCLASSIFIED//FQA: QFFI&l11J.k W&liii Q•lklf Table 1. Summary of the Properties of the Log normal Distribution That Applies to the Random Variable N = Number of ET Communicating Civilizations in the Galaxy Random variable Probability distribution Probability density function Mean value Variance Standard deviation All the moments, i.e. k-th moment Mode ( = abscissa of the log normal peak) Value of the Mode Peak Median ( = fifty-fifty probability value for N) Skewness Kurtosis Expression of .u in terms of the lower (ai) and upper (b1) limits of the Drake uniform input random variables Di Expression of a 2 in terms of the lower (a,) and upper (bi) limits of the Drake uniform inout random variables D, N = number of communicating ET civilizations in qalaxy Loqnormal (in(,i) ,11)' = _ ,/I ,-cr- 11 m,Je - 11 pcak - ( < " j . ( 1 -u ----:;- N 11,,.,dc)= ~ ·e • ·e - V21T /J' nrdian = m = e·" (11;;:: 0) , _ ~ , _ ~I- a,b,[h,(b,)-h,(a;)]' a - ,t,...PY - £..J 1-l ' 1-l (b,. - (I, f 7. An Example Explaining the Statistical Drake Equation To understand how things work in practice for the statistical Drake equation, please consider the following table 2. It is made up of three columns: • The first column on the left lists the seven input sheer numbers that also become • The mean values (middle column). • Finally the last column on the right lists the seven input standard deviations. 15 UNCLASSIFIED/ fffUl 8ffl@Isf\k Wfiliii Q•lklf
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 55 pages are in the text index: search them above, or from the library's search.