Nils-Eric Sahlin

The role of second-order probabilities in decision making

The importance, legitimacy and role of second-order probabilities are discussed. Two descriptive models of the use of second-order probabilities in decisions are presented. The results of two empirical studies of the effects of second-order probabilities upon the rank orderings of bets are summarized briefly. The bets were of three basic types and involved a wide variety of first- and second-order probabilities as subjectively assessed by the subjects. Support was obtained for the assumption that the majority of subjects make use of the one model or the other. It is suggested that greater attention should be paid to second-order probabilities, both from a normative and descriptive standpoint.

Epistemic risk: The significance of knowing what one does not know

It is a well-established psychological result that the unknown and unwanted in particular scare us.1 A thinner ozone-layer is felt to be a considerable risk. On a more mundane level, situating a gas-tank in a suburban neighbourhood or eating fish with an unknown level of dioxin provokes a similar feeling of risk-taking.

On Higher Order Beliefs

This paper is about higher order beliefs and probabilities. First, I will show how higher order beliefs add to our comprehension of judgmental and decision processes. Second, some well-known arguments against higher order beliefs represented in terms of higher order probabilities, as well as counter arguments, will be summarized and scrutinized. Third, an unpublished note by F. P. Ramsey on “unknown probabilities” will be discussed.

Decision science: from Ramsey to dual process theories

The hypothesis that human reasoning and decision-making can be roughly modeled by Expected Utility Theory has been at the core of decision science. Accumulating evidence has led researchers to modify the hypothesis. One of the latest additions to the field is Dual Process theory, which attempts to explain variance between participants and tasks when it comes to deviations from Expected Utility Theory. It is argued that Dual Process theories at this point cannot replace previous theories, since they, among other things, lack a firm conceptual framework, and have no means of producing independent evidence for their case.

Diagnostic accuracy of different caries risk assessment methods. A systematic review

OBJECTIVES To evaluate the accuracy of different methods used to identify individuals with increased risk of developing dental coronal caries. DATA Studies on following methods were included: previous caries experience, tests using microbiota, buffering capacity, salivary flow rate, oral hygiene, dietary habits and sociodemographic variables. QUADAS-2 was used to assess risk of bias. Sensitivity, specificity, predictive values, and likelihood ratios (LR) were calculated. Quality of evidence based on ≥3 studies of a method was rated according to GRADE. SOURCES PubMed, Cochrane Library, Web of Science and reference lists of included publications were searched up to January 2015. STUDY SELECTION From 5776 identified articles, 18 were included. Assessment of study quality identified methodological limitations concerning study design, test technology and reporting. No study presented low risk of bias in all domains. Three or more studies were found only for previous caries experience and salivary mutans streptococci and quality of evidence for these methods was low. Evidence regarding other methods was lacking. For previous caries experience, sensitivity ranged between 0.21 and 0.94 and specificity between 0.20 and 1. Tests using salivary mutans streptococci resulted in low sensitivity and high specificity. For children with primary teeth at baseline, pooled LR for a positive test was 3 for previous caries experience and 4 for salivary mutans streptococci, given a threshold ≥10(5) CFU/ml. CONCLUSIONS Evidence on the validity of analysed methods used for caries risk assessment is limited. As methodological quality was low, there is a need to improve study design. CLINICAL SIGNIFICANCE Low validity for the analysed methods may lead to patients with increased risk not being identified, whereas some are falsely identified as being at risk. As caries risk assessment guides individualized decisions on interventions and intervals for patient recall, improved performance based on best evidence is greatly needed.

Baconian Inductivism in Research on Human Decision-Making

The paper discusses the pros and cons of inductive research methods. It is argued that, despite the profusion of good arguments against this scientific strategy, it is frequently employed, for example in psychology. A case probe taken from the realm of cognitive psychology is used as an illustration.

On Second Order Probabilities and the Notion of Epistemic Risk

Second or higher order probabilities have commonly been viewed with scepticism by those working within the realm of probability and decision theory. The aim of the present note is to show how the notion of second order probabilities can add to our understanding of judgmental and decision processes and how the traditional framework of Bayesian decision theory can be extended in a fruitful way by taking such entities into account. Section one consists of a brief account of arguments put forth against higher order probabilities as well as of counterarguments. In order to provide an example of the applicability of second order probabilities a decision theory encompassing such probabilities will be presented in section two. In section three I will try to emphasize the value of second order probabilities for a deeper and more complete understanding of the notion of risk.

Ethical theory and the philosophy of risk: first thoughts

Contemporary psychological research has shown that if we are judged by the standards of classical models of rationality our decision‐making abilities can be seriously questioned. We are more or less irrational. The article investigates how this ‘fact of irrationality’ affects the way normative ethical theories should be formulated and the extent to which currently dominant ethical theories can be taken seriously as normative ideals of actual human decision‐making. It is argued that these theories tend to presuppose a too unified and rationalistic account of human agency and that there is reason to turn attention instead to a level of ethical theorizing that lies between traditional ethical theory and applied ethics. It is also argued that given such an approach, matters of risk and uncertainty should be more directly integrated into basic ethical theorizing than what is traditionally the case.

The Evidentiary Value Model

Theories of evidence and theories of knowledge are intimately linked together. And there are many competing theories of evidence. One way to approach them is by way of looking at the theories of knowledge which are their bedrock.

The significance of empirical evidence for developments in the foundations of decision theory

This paper concerns the question of the significance of empirical evidence for developments in the foundations of decision theory. I will argue that a particular type of empirical findings is of crucial importance for how the theory develops. My position will thus be in sharp contrast to what I take to be the general view of the matter, i.e. that empirical findings have been and should be without significance for developments in the foundations of decision theory. In order to be able to outline more fully my aims and ideas a survey of the traditional theory of decision making, the Bayesian theory, is called for.