Gauge Coupling Unification in MSSM + 5 Flavors

We investigate gauge coupling unification at 2-loops for theories with 5 extra vectorlike SU(5) fundamentals added to the MSSM. This is a borderline case where unification is only predicted in certain regions of parameter space. We establish a lower bound on the scale for the masses of the extra flavors, as a function of the sparticle masses. Models far outside of the bound do not predict unification at all (but may be compatible with unification), and models outside but near the boundary cannot reliably claim to predict it with an accuracy comparable to the MSSM prediction. Models inside the boundary can work just as well as the MSSM.Comment: 28 pages, 13 figures. Added references, fixed minor typos. No changes to content. Page count was incorrect in v1 Comment

Analysis-of-marginal-Tail-Means (ATM): a robust method for discrete black-box optimization

We present a new method, called Analysis-of-marginal-Tail-Means (ATM), for effective robust optimization of discrete black-box problems. ATM has important applications to many real-world engineering problems (e.g., manufacturing optimization, product design, molecular engineering), where the objective to optimize is black-box and expensive, and the design space is inherently discrete. One weakness of existing methods is that they are not robust: these methods perform well under certain assumptions, but yield poor results when such assumptions (which are difficult to verify in black-box problems) are violated. ATM addresses this via the use of marginal tail means for optimization, which combines both rank-based and model-based methods. The trade-off between rank- and model-based optimization is tuned by first identifying important main effects and interactions, then finding a good compromise which best exploits additive structure. By adaptively tuning this trade-off from data, ATM provides improved robust optimization over existing methods, particularly in problems with (i) a large number of factors, (ii) unordered factors, or (iii) experimental noise. We demonstrate the effectiveness of ATM in simulations and in two real-world engineering problems: the first on robust parameter design of a circular piston, and the second on product family design of a thermistor network

Measuring and Interpreting Expectations of Equity Returns

We analyze probabilistic expectations of equity returns elicited in the Survey of Economic Expectations in 1999 %uF8182001 and in the Michigan Survey of Consumers in 2002 %uF8182004. Our empirical findings suggest that individuals use interpersonally variable but intrapersonally stable processes to form their expectations. We therefore propose to think of the population as a mixture of expectations types, each forming expectations in a stable but different way. We use our expectations data to learn about the prevalence of several specific types suggested by research in conventional and behavioral finance, but conclude that these types do not adequately explain the diverse expectations held by the population.

How Should We Measure Consumer Confidence (Sentiment)? Evidence from the Michigan Survey of Consumers

The Michigan Index of Consumer Sentiment (ICS) and other indices of consumer confidence are prominent in public discourse on the economy but have little presence in modern economic research. The sparsity of modern research follows an earlier period when economists scrutinized in some depth the methods and data used to produce consumer confidence indices. The literature to date has focused on the predictive power of the survey data used to form the indices; there has been very little study of their micro foundations. This paper analyzes the responses to eight expectations questions that have appeared on the Michigan Survey of Consumers in the period June 2002 through May 2003. Four questions elicit micro and macroeconomic expectations in the traditional qualitative manner; two are components of the ICS. Four questions use a percent chance' format to elicit subjective probabilities of micro and macroeconomic events; versions of these questions have previously appeared in the Survey of Economic Expectations.

Using Expectations Data to Study Subjective Income Expectations

We have collected data on the one-year-ahead income expectations of members of American households in our Survey of Economic Expectations (SEE), a module of a national continuous telephone survey conducted at the University of Wisconsin. The income- expectations questions take this form: "What do you think is the percent chance (or what are the chances out of 100) that your total household income, before taxes, will be less than Y over the next 12 months?" We use the responses to a sequence of such questions posed for different income thresholds Y to estimate each respondent's subjective probability distribution for next year's household income. We use the estimates to study the cross-sectional variation in income expectations one year into the future.

Perceptions of Economic Insecurity: Evidence from the Survey of Economic Expectations

We have recently initiated the Survey of Economic Expectations (SEE) to learn how Americans perceive their near-term futures. This paper uses SEE data on over two thousand labor force participants interviewed in 1994 and 1995 to describe how Americans in the labor force perceive the risk of near-term economic misfortune. We measure economic insecurity through responses to questions eliciting subjective probabilities of three events in the year ahead: absence of health insurance, victimization by burglary, and job loss. With item response rates exceeding 98 percent, respondents clearly are willing to answer the expectations questions and they appear to do so in a meaningful way. Using the responses to classify individuals as relatively secure, relatively insecure, and highly insecure, we find that respondents with a high risk of one adverse outcome tend also to perceive high risks of the other outcomes. Economic insecurity tends to decline with age and with schooling. Black respondents perceive much greater insecurity than do whites, especially among males. Within the period 1994-1995, we find some time-series variation in insecurity but no clear trends. We find that expectations and realizations of health insurance coverage and of jobs tend to match up quite closely, but respondents substantially overpredict the risk of burglary.