Multiple testing via FDRLFDR_L for large-scale imaging data

The multiple testing procedure plays an important role in detecting the presence of spatial signals for large-scale imaging data. Typically, the spatial signals are sparse but clustered. This paper provides empirical evidence that for a range of commonly used control levels, the conventional $\operatorname {FDR}$ procedure can lack the ability to detect statistical significance, even if the $p$-values under the true null hypotheses are independent and uniformly distributed; more generally, ignoring the neighboring information of spatially structured data will tend to diminish the detection effectiveness of the $\operatorname {FDR}$ procedure. This paper first introduces a scalar quantity to characterize the extent to which the "lack of identification phenomenon" ($\operatorname {LIP}$) of the $\operatorname {FDR}$ procedure occurs. Second, we propose a new multiple comparison procedure, called $\operatorname {FDR}_L$, to accommodate the spatial information of neighboring $p$-values, via a local aggregation of $p$-values. Theoretical properties of the $\operatorname {FDR}_L$ procedure are investigated under weak dependence of $p$-values. It is shown that the $\operatorname {FDR}_L$ procedure alleviates the $\operatorname {LIP}$ of the $\operatorname {FDR}$ procedure, thus substantially facilitating the selection of more stringent control levels. Simulation evaluations indicate that the $\operatorname {FDR}_L$ procedure improves the detection sensitivity of the $\operatorname {FDR}$ procedure with little loss in detection specificity. The computational simplicity and detection effectiveness of the $\operatorname {FDR}_L$ procedure are illustrated through a real brain fMRI dataset.Comment: Published in at http://dx.doi.org/10.1214/10-AOS848 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

China's Sovereign Wealth Fund : Weakness and Challenges

The establishment of sovereign wealth funds in large developing countries has generated hot debate among participants in the international financial market. When accumulated foreign exchange reserves surpass a sufficient and an appropriate level, the costs, risks and impacts on the macro-economy of countries holding reserves need to be considered. The Chinese Government established China Investment Corporation (CIC) in 2007 to diversify its investment of foreign reserves and to raise investment income. However, because of certain conflicts of interest and institution-design caveats, CIC possesses some internal weakness, including a vague orientation, mixed investment strategies and inefficient bureaucratic style. Although the subprime crisis has softened certain regulations and lessened rejection by the USA of CIC potential investments, the increased volatility and uncertainty of the market means that CIC is facing some new challenges in terms of its investment decisions. Moreover, CIC is competing with other Chinese investment institutions for injections of funds from the Chinese Government.CIC, external challenge, internal weakness, foreign exchange reserve management