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1.
本文探讨了影响分析化学实验结果的因素,指出溶液的酸度、试剂的浓度,用量、加入顺序和溶剂等都对分析实验的结果产生影响,并分析了其原因。 相似文献
2.
B超的滥用、强烈的男孩偏好以及对非法流产行为监控的失效共同构成我国出生性别比偏高的充要条件,三者中任一条件不满足都不可能出现出生性别比偏高。尽管B超发明和滥用前出生性别比并没有异常,但也不能说出生性别比偏高与受教育水平、传统文化等因素无关。事实上,这些因素通过影响男孩偏好和B超的可获得性而影响出生性别比。由此出发,促进出生性别比回复正常,短期内应标本兼治,以治标为主———坚决禁止B超的滥用,关键是加强立法和管理;长期内则必须治本———消除男孩偏好,关键是加速农村城市化。 相似文献
3.
Charles F. Manski 《Theory and Decision》1988,25(1):79-104
This paper studies two models of rational behavior under uncertainty whose predictions are invariant under ordinal transformations of utility. The quantile utility model assumes that the agent maximizes some quantile of the distribution of utility. The utility mass model assumes maximization of the probability of obtaining an outcome whose utility is higher than some fixed critical value. Both models satisfy weak stochastic dominance. Lexicographic refinements satisfy strong dominance.The study of these utility models suggests a significant generalization of traditional ideas of riskiness and risk preference. We define one action to be riskier than another if the utility distribution of the latter crosses that of the former from below. The single crossing property is equivalent to a minmax spread of a random variable. With relative risk defined by the single crossing criterion, the risk preference of a quantile utility maximizer increases with the utility distribution quantile that he maximizes. The risk preference of a utility mass maximizer increases with his critical utility value. 相似文献
4.
Rubinstein (1982) considered the problem of dividing a given surplus between two players sequentially, and then proposed a model in which the two players alternately make and respond to each other's offers through time. He further characterized the perfect equilibrium outcomes, which depend on the players time preferences and order of moves. Using both equal and unequal bargaining cost conditions and an unlimited number of rounds, two experiments were designed to compare the perfect equilibrium model to alternative models based on norms of fairness. We report analyses of final agreements, first offers, and number of bargaining rounds, which provide limited support to the perfect equilibrium model, and then conclude by recommending a shift in focus from model testing to specification of the conditions favoring one model over another. 相似文献
5.
Moncef Abbas 《Theory and Decision》1995,39(2):115-126
This article proves that all complete preference structures where the strict preference relation (P) has no circuit admit a representation by intervals of the real line; the rule for deciding whether an interval is indifferent or preferred to another is less straightforward than for interval orders: strict preference is indeed compatible with a certain degree of overlapping of intervals, the allowed degree being specified by means of a so-called tolerance function. 相似文献
6.
This paper contributes to a theory of rational choice for decision-makers with incomplete preferences due to partial ignorance, whose beliefs are representable as sets of acceptable priors. We focus on the limiting case of `Complete Ignorance' which can be viewed as reduced form of the general case of partial ignorance. Rationality is conceptualized in terms of a `Principle of Preference-Basedness', according to which rational choice should be isomorphic to asserted preference. The main result characterizes axiomatically a new choice-rule called `Simultaneous Expected Utility Maximization'. It can be interpreted as agreement in a bargaining game (Kalai-Smorodinsky solution) whose players correspond to the (extremal) `acceptable priors' among which the decision maker has suspended judgment. An essential but non-standard feature of Simultaneous Expected Utility choices is their dependence on the entire choice set. This is justified by the conception of optimality as compromise rather than as superiority in pairwise comparisons. 相似文献
7.
T. Nagamitsu Kuniyasu Momose Tamiji Inoue David W. Roubik 《Researches on Population Ecology》1999,41(2):195-202
Floral resource partitioning among stingless bees (Trigona, Meliponini, Apidae) in a lowland rain forest in Sarawak, Malaysia, was investigated using tree towers and walkways in a
4-year study that included a general flowering period. We obtained 100 collections of insect visitors to flowers of varying
floral location and shape representing 81 plant species. The tendency of 11 species of stingless bees to visit specific flowers
with a particular floral location and shape was analyzed by logistic regression analysis. This analysis showed that the proportion
of flower visitor collections containing Trigona fuscobalteata and T. melanocephala differed according to floral location. The former was frequently collected at canopy and gap flowers, whereas the latter
was most often collected at understory flowers. The analysis also suggested that T. erythrogastra was more rarely collected at shallow flowers than at deep flowers. Analysis of the pollen diets of T. collina, T. fuscobalteata, T. melanocephala, and T. melina revealed that similarity of pollen sources differed among the six permutated pairs of the four species. The lowest mean rank
of similarity found was between T. fuscobalteata and T. melanocephala. This result supports the hypothesis that preference in visiting flowers in different locations leads to pollen resource
partitioning.
Received: May 14, 1997 / Accepted: April 23, 1999 相似文献
8.
9.
文章发展了一个均衡模型,从微观机理角度解释了为什么资产价格会发生不频繁的跳跃行为.在该模型中,投资者学习不可直接观测的、真实的经济系统状态并为此支付成本的行为诱发了资产价格的跳跃行为.而投资者是否选择学习的行为则取决于投资者的偏好参数和收入的条件波动率. 相似文献
10.
Polynomial spline regression models of low degree have proved useful in modeling responses from designed experiments in science and engineering when simple polynomial models are inadequate. Where there is uncertainty in the number and location of the knots, or breakpoints, of the spline, then designs that minimize the systematic errors resulting from model misspecification may be appropriate. This paper gives a method for constructing such all‐bias designs for a single variable spline when the distinct knots in the assumed and true models come from some specified set. A class of designs is defined in terms of the inter‐knot intervals and sufficient conditions are obtained for a design within this class to be all‐bias under linear, quadratic and cubic spline models. An example of the construction of all‐bias designs is given. 相似文献