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Energy Systems and Technologies for the Coming Century ...

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where I (·) is <strong>the</strong> indicator function. Each observation contributes two terms to <strong>the</strong>loglikelihood function. The first isjWtj , wherey tj , <strong>and</strong> <strong>the</strong> second is minus <strong>the</strong>logarithm of <strong>the</strong> denominator that appears in equation (1). The above explanation dealswith multinomial probability <strong>and</strong> loglinear models. However our study is based on <strong>the</strong>nested MNL model (McFadden, 1981). There is a range of advantages to employingMNL model instead of a series of regular logistic regressions. First, when applying all<strong>the</strong> data <strong>for</strong> <strong>the</strong> estimation ra<strong>the</strong>r than subsets so, <strong>the</strong> estimates are prompter. Secondly,<strong>the</strong>re follows a logical relationship amidst <strong>the</strong> choices, <strong>for</strong> instance, if an individualprefers to travel by car to bus <strong>and</strong> prefers motorcycle to car, he should prefer amotorcycle to a bus, <strong>and</strong> his relative orientation should be a definite variety ofcombination of <strong>the</strong> individual preferences. The coefficients once generated representhow <strong>the</strong> logarithmized probability of choosing one alternative instead of <strong>the</strong> baseoutcome changes if variable changes from 0 to 1.Various determinants of <strong>the</strong> mode to transport to work are considered. Table 1 present adescription of variables used in <strong>the</strong> MNL model. The choice of transport mode isclassified under three distinct categories namely: car, bus <strong>and</strong> o<strong>the</strong>rs (motorcycle, taxis,company van/car <strong>and</strong> on foot). Demographic characteristics include age, gender,household size, education <strong>and</strong> income level. The travel characteristics described so farconceal significant differences between genders. Males travelling by car outweigh femalecar travelers by more than <strong>the</strong> double as revealed by <strong>the</strong> survey. A slightly higherproportion of women are bus passengers. Travelling by motorcycle <strong>and</strong> o<strong>the</strong>r mode tendsto be more of a male characteristic. Next, education level which includes secondary,Risø International <strong>Energy</strong> Conference 2011 Proceedings Page 392

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