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Halbert White - One of the best experts on this subject based on the ideXlab platform.

  • can mutual fund stars really pick stocks new evidence from a bootstrap analysis
    Journal of Finance, 2006
    Co-Authors: Robert Kosowski, Russ Wermers, Allan Timmermann, Halbert White
    Abstract:

    We apply a new bootstrap statistical technique to examine the performance of the U.S. openend, domestic-equity mutual fund industry over the 1975 to 2002 period. Specifically, we bootstrap the joint Distribution of performance measures (\alphas) across all funds to determine whether managers of high-alpha funds are simply the luckiest in a large field of managers, or whether they possess genuine stockpicking skills. This bootstrap approach is necessary because the cross-section of mutual fund alphas has a complex, Non-Normal Distribution{due to heterogeneous risk-taking by funds as well as Non-Normalities in individual fund alpha Distributions. Our bootstrap approach reveals findings that differ from many past studies. Specifically, we find that a sizable minority of managers really do pick stocks well enough to more than cover their costs. Moreover, our bootstrap indicates that the superior alphas of these managers persist.

  • can mutual fund stars really pick stocks new evidence from a bootstrap analysis
    Social Science Research Network, 2005
    Co-Authors: Robert Kosowski, Russ Wermers, Allan Timmermann, Halbert White
    Abstract:

    We apply a new bootstrap statistical technique to examine the performance of the U.S. open-end, domestic-equity mutual fund industry over the 1975 to 2002 period. This bootstrap approach is necessary because the cross-section of mutual fund alphas has a complex, Non-Normal Distribution – due to heterogeneous risk-taking by funds as well as Non-Normalities in individual fund alpha Distributions. Our bootstrap approach reveals findings that differ from many past studies. Specifically, we find that a sizable minority of managers pick stocks well enough to more than cover their costs; moreover, the superior alphas of these managers persist.

Allan Timmermann - One of the best experts on this subject based on the ideXlab platform.

  • can mutual fund stars really pick stocks new evidence from a bootstrap analysis
    Journal of Finance, 2006
    Co-Authors: Robert Kosowski, Russ Wermers, Allan Timmermann, Halbert White
    Abstract:

    We apply a new bootstrap statistical technique to examine the performance of the U.S. openend, domestic-equity mutual fund industry over the 1975 to 2002 period. Specifically, we bootstrap the joint Distribution of performance measures (\alphas) across all funds to determine whether managers of high-alpha funds are simply the luckiest in a large field of managers, or whether they possess genuine stockpicking skills. This bootstrap approach is necessary because the cross-section of mutual fund alphas has a complex, Non-Normal Distribution{due to heterogeneous risk-taking by funds as well as Non-Normalities in individual fund alpha Distributions. Our bootstrap approach reveals findings that differ from many past studies. Specifically, we find that a sizable minority of managers really do pick stocks well enough to more than cover their costs. Moreover, our bootstrap indicates that the superior alphas of these managers persist.

  • can mutual fund stars really pick stocks new evidence from a bootstrap analysis
    Social Science Research Network, 2005
    Co-Authors: Robert Kosowski, Russ Wermers, Allan Timmermann, Halbert White
    Abstract:

    We apply a new bootstrap statistical technique to examine the performance of the U.S. open-end, domestic-equity mutual fund industry over the 1975 to 2002 period. This bootstrap approach is necessary because the cross-section of mutual fund alphas has a complex, Non-Normal Distribution – due to heterogeneous risk-taking by funds as well as Non-Normalities in individual fund alpha Distributions. Our bootstrap approach reveals findings that differ from many past studies. Specifically, we find that a sizable minority of managers pick stocks well enough to more than cover their costs; moreover, the superior alphas of these managers persist.

Michael B. Ranke - One of the best experts on this subject based on the ideXlab platform.

  • Reference ranges for serum concentrations of lutropin (LH), follitropin (FSH), estradiol (E2), prolactin, progesterone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), cortisol and ferritin in neonates, children and young
    Clinical Chemistry and Laboratory Medicine, 2002
    Co-Authors: Martin W. Elmlinger, Wolfgang Kühnel, Michael B. Ranke
    Abstract:

    The aim of this study was to establish reference ranges for children (neonates to young adults), for serum lutropin (LH), follitropin (FSH), estradiol (E2), progesterone, prolactin, sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), cortisol and ferritin, using the nonisotopic, automated chemiluminescence immunoassay system, Immulite (DPC). Serum samples from 762 children (369 female; age 1 day to 19 years) were examined. Of these, 381 were classified as pubertal. Due to Non-Normal Distribution, the 2.5th, 50th and 97.5th percentiles (central 95% interval) were calculated for each group. Statistical differences between the reference ranges were analyzed with respect to age, sex and the stage of sexual maturation. The median concentrations of E2, prolactin, progesterone, DHEAS, cortisol and ferritin were higher during the first 2 weeks post-partum than thereafter. The largest difference was seen with prolactin, which showed up to 27-fold higher values during this period. In contrast, before the onset of puberty, hardly any sex difference was observed and all analyte concentrations remained relatively constant, apart from SHBG which increased steadily after the neonatal period. The increase of gonadal activity in females with the onset of sexual maturation included an increase in LH and FSH, which was accompanied by a strong increase in E2, progesterone and prolactin. Cortisol increased to a lesser extent during puberty. In males, the increase in the median concentrations of the hormones was smaller, except for DHEAS. The concentration of ferritin was high in the neonatal period but did not change during sexual maturation. Our findings agree with earlier studies. The calculated reference intervals can be used to assess the development of children, particularly for measurements performed by the Immulite and Immulite 2000 chemiluminescence assay systems.

  • reference intervals from birth to adulthood for serum thyroxine t4 triiodothyronine t3 free t3 free t4 thyroxine binding globulin tbg and thyrotropin tsh
    Clinical Chemistry and Laboratory Medicine, 2001
    Co-Authors: Martin W. Elmlinger, Werner Kuhnel, Hansgeorg Lambrecht, Michael B. Ranke
    Abstract:

    Disorders in thyroid function can impair normal development in children. Therefore it was our aim to establish reference intervals for serum triiodothyronine (T3), free T3 (fT3), thyroxine (T4), free T4 (fT4), thyroxine binding globulin (TBG) and thyrotropin (TSH) which are applicable from birth to adulthood by using the non-isotopic automated chemiluminescence immunoassay system, Immulite (DPC Los Angeles, USA). Serum samples from 762 euthyroid newborns, children and adolescents (369 female, 393 male; age 1 day to 19 years) were examined; of these, 381 were classified as pubertal. Due to Non-Normal Distribution, the 2.5th, 50th and 97.5th percentiles (the central 95% interval) were calculated for each group. The median concentrations of T4, fT4 and TSH were up to 3.2-fold higher during the first 2 weeks, while T4 increased during the first month of life. The concentrations in all age groups showed no sex differences. From 1 year onwards, the concentration of all parameters tended to decrease until adult age, with the exception of TBG which increased by >60% (p<0.02) and reached a maximum at approximately 5 years of age. The findings underscore the fact that thyroid hormones are not associated with sexual development, except for TBG, which decreased slightly (p<0.04) between Tanner stages 1 and 5. However, the reference intervals established here demonstrate that marked changes occur in concentrations of thyroid hormones after the neonatal period. Our findings complement these of earlier studies. The developed reference intervals can be used to assess the thyroid status of patients, particularly if the measurements are done on the Immulite/Immulite 2000 system.

Robert Kosowski - One of the best experts on this subject based on the ideXlab platform.

  • can mutual fund stars really pick stocks new evidence from a bootstrap analysis
    Journal of Finance, 2006
    Co-Authors: Robert Kosowski, Russ Wermers, Allan Timmermann, Halbert White
    Abstract:

    We apply a new bootstrap statistical technique to examine the performance of the U.S. openend, domestic-equity mutual fund industry over the 1975 to 2002 period. Specifically, we bootstrap the joint Distribution of performance measures (\alphas) across all funds to determine whether managers of high-alpha funds are simply the luckiest in a large field of managers, or whether they possess genuine stockpicking skills. This bootstrap approach is necessary because the cross-section of mutual fund alphas has a complex, Non-Normal Distribution{due to heterogeneous risk-taking by funds as well as Non-Normalities in individual fund alpha Distributions. Our bootstrap approach reveals findings that differ from many past studies. Specifically, we find that a sizable minority of managers really do pick stocks well enough to more than cover their costs. Moreover, our bootstrap indicates that the superior alphas of these managers persist.

  • can mutual fund stars really pick stocks new evidence from a bootstrap analysis
    Social Science Research Network, 2005
    Co-Authors: Robert Kosowski, Russ Wermers, Allan Timmermann, Halbert White
    Abstract:

    We apply a new bootstrap statistical technique to examine the performance of the U.S. open-end, domestic-equity mutual fund industry over the 1975 to 2002 period. This bootstrap approach is necessary because the cross-section of mutual fund alphas has a complex, Non-Normal Distribution – due to heterogeneous risk-taking by funds as well as Non-Normalities in individual fund alpha Distributions. Our bootstrap approach reveals findings that differ from many past studies. Specifically, we find that a sizable minority of managers pick stocks well enough to more than cover their costs; moreover, the superior alphas of these managers persist.

Muhammad Kashif - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of modified non normal process capability index and its bootstrap confidence intervals
    IEEE Access, 2017
    Co-Authors: Muhammad Kashif, Muhammad Aslam, Chi-hyuck Jun, Ali Hussein Almarshadi, Muhammad Imran Khan
    Abstract:

    Process capability index (PCI) is used to quantify the process performance and is becoming an attracted area of research. A variability measure plays an important role in PCI. The interquartile range (IQR) or the median absolute deviation (MAD) is commonly used for a variability measure in estimating PCI when a process follows a Non-Normal Distribution In this paper, the efficacy of the IQR and MAD-based PCIs was evaluated under low, moderate, and high asymmetric behavior of the Weibull Distribution using different sample sizes through three different bootstrap confidence intervals. The result reveals that MAD performs better than IQR, because the former produced less bias and mean square error. Also, the percentile bootstrap confidence interval is recommended for use, because it has less average width and high coverage probability.

  • Capability Indices for Non-Normal Distribution Using Gini’s Mean Difference as Measure of Variability
    IEEE Access, 2016
    Co-Authors: Muhammad Kashif, Muhammad Aslam, Ali Hussein Al-marshadi, Chi-hyuck Jun
    Abstract:

    This paper investigates the efficiency of Gini’s mean difference (GMD) as a measure of variability in two commonly used process capability indices (PCIs), i.e., Cp and Cpk. A comparison has been carried out to evaluate the performance of GMD-based PCIs and Pearn and Chen quantile-based PCIs under low, moderate, and high asymmetry using Weibull Distribution. The simulation results, under low and moderate asymmetric condition, indicate that GMD-based PCIs are more close to target values than quantile approach. Beside point estimation, nonparametric bootstrap confidence intervals, such as standard, percentile, and bias corrected percentile with their coverage probabilities also have been calculated. Using quantile approach, bias corrected percentile (BCPB) method is more effective for both Cp and Cpk, where as in case of GMD, both BCPB and percentile bootstrap method can be used to estimate the confidence interval of Cp and Cpk, respectively.