7,556 research outputs found
A NOTE ON HOUSING WEALTH AND PRIVATE CONSUMPTION
This paper analyses the relationship between house prices and private consumption of the US economy. Based on Granger's causality test, we ask whether this relationship is driven by causality or whether it is merely an ambiguous connection. Based on latest quartely data, our results show that there is indeed a causal relationship with changes in house prices affeting private consumption, fundamentally supporting economic theory. Considering existing research, it is therefore suggested that the US economy is at the outset of a severe economic downturn, confirming pessimist's expectations.Wealth effect; House prices; Consumption; Granger causality
State Discrimination with Post-Measurement Information
We introduce a new state discrimination problem in which we are given
additional information about the state after the measurement, or more
generally, after a quantum memory bound applies. In particular, the following
special case plays an important role in quantum cryptographic protocols in the
bounded storage model: Given a string x encoded in an unknown basis chosen from
a set of mutually unbiased bases, you may perform any measurement, but then
store at most q qubits of quantum information. Later on, you learn which basis
was used. How well can you compute a function f(x) of x, given the initial
measurement outcome, the q qubits and the additional basis information? We
first show a lower bound on the success probability for any balanced function,
and any number of mutually unbiased bases, beating the naive strategy of simply
guessing the basis. We then show that for two bases, any Boolean function f(x)
can be computed perfectly if you are allowed to store just a single qubit,
independent of the number of possible input strings x. However, we show how to
construct three bases, such that you need to store all qubits in order to
compute f(x) perfectly. We then investigate how much advantage the additional
basis information can give for a Boolean function. To this end, we prove
optimal bounds for the success probability for the AND and the XOR function for
up to three mutually unbiased bases. Our result shows that the gap in success
probability can be maximal: without the basis information, you can never do
better than guessing the basis, but with this information, you can compute f(x)
perfectly. We also exhibit an example where the extra information does not give
any advantage at all.Comment: twentynine pages, no figures, equations galore. v2 thirtyone pages,
one new result w.r.t. v
Joint Transmit and Receive Filter Optimization for Sub-Nyquist Delay-Doppler Estimation
In this article, a framework is presented for the joint optimization of the
analog transmit and receive filter with respect to a parameter estimation
problem. At the receiver, conventional signal processing systems restrict the
two-sided bandwidth of the analog pre-filter to the rate of the
analog-to-digital converter to comply with the well-known Nyquist-Shannon
sampling theorem. In contrast, here we consider a transceiver that by design
violates the common paradigm . To this end, at the receiver, we
allow for a higher pre-filter bandwidth and study the achievable
parameter estimation accuracy under a fixed sampling rate when the transmit and
receive filter are jointly optimized with respect to the Bayesian
Cram\'{e}r-Rao lower bound. For the case of delay-Doppler estimation, we
propose to approximate the required Fisher information matrix and solve the
transceiver design problem by an alternating optimization algorithm. The
presented approach allows us to explore the Pareto-optimal region spanned by
transmit and receive filters which are favorable under a weighted mean squared
error criterion. We also discuss the computational complexity of the obtained
transceiver design by visualizing the resulting ambiguity function. Finally, we
verify the performance of the optimized designs by Monte-Carlo simulations of a
likelihood-based estimator.Comment: 15 pages, 16 figure
Measuring Concentration in Data with an Exogenous Order
Concentration measures order the statistical units under observation according to their market share. However, there are situations where an order according to an exogenous variable is more appropriate or even
required. The present article introduces a generalized definition of market concentration and defines a corresponding concentration measure. It is shown that this generalized concept of market concentration satisfies the common axioms of (classical) concentration measures. In an application
example, the proposed approach is compared with classical concentration measures; the data are transfer spendings of German
Bundesliga soccer teams, the ``obvious'' exogenous order of the teams is the league ranking
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