PrincipalComponentsAnalysis 主成分分析知识研讨.ppt

CHAPTER 4:Principal Components Analysis(主成份分析);Introduction;The first principal component, ξ1, accounts for the maximum variance in the data, the second principal component, ξ2, accounts for the maximum variance that has not been accounted for by the first principal component, and so on.;Dimension Reduction (資料構面縮減) Ofir和Simonson在2001年藉著Cacioppo、Petty以及Kao在1984的研究發展出18個問項來評估need for cognition，見表4.1。 ;TABLE 4.1 Eighteen items used in measuring a survey respondent’s “need for cognition” Item Response C1 I prefer complex to simple problems. C2 I like to have the responsibility of handling a situation that requires a lot of thinking. C3 Thinking is not my idea of fun.（R） C4 I would rather do something requiring little thought than something that is sure to challenge my thinking abilities. C5 I try to anticipate and avoid situations where there is a likely chance that I will have to think in depth about something.（R） C6 I find satisfaction in deliberating hard for long hours. C7 I only think as hard as I have to.（R） C8 I prefer to think about small daily projects to long-term ones.（R） C9 I like tasks that require little thought once I’ve learned them.（R） C10 The idea of relying on thought to make my way to the top appeals to me. C11 I really enjoy a task that involves coming up with new solutions to problems. C12 Learning new ways to think doesn’t excite me much.（R） C13 I prefer my life to be filled with puzzles that I must solve. C14 The notion of thinking abstractly is appealing to me. C15 I prefer tasks that are intellectual , difficult , and important to ones that do not require much thought. C16 I feel relief rather than satisfaction after completing a task that required a lot of mental effort.（R） C17 It’s enough for me that something gets the job done ; I don’t care how or why it works.（R） C18 I usually end up deliberating about issues even when t