Evaluating Macroeconometric Modelling with Regard to Usefulness: a Survey

Macroeconometric models have during the last 40 years played an important role as a tool to guide decision making in public as well as private macroeconomic institutions. However, such models have not been much used in academic circles. We argue that macroeconometric models have problems both with regard to internal and external validity. Although the science of econometrics has partly answered the problem of internal validity, macroeconometric modelling is still dismissed by theorists as inappropriate for theoretical development. We find that the argument over how to evaluate macroeconometric modelling can be viewed as a result of the relationship between observed economic variables and economic theory.econometric models, theory of science

Liquidity provision in the overnight foreign exchange market

We presents evidence that non-financial customers are the main liquidity providers in the overnight foreign exchange market using a unique daily data set covering almost all transactions in the SEK/EUR market over almost ten years. Two main findings support this: (i) The net position of non-financial customers is negatively correlated with the exchange rate, opposed to the positive correlation found for financial customers; (ii) Changes in net position of non-financial customers are forecasted by changes in net position of financial customers, indicating that non-financial customers take a passive role consistent with liquidity provision.Microstructure, International finance, Liquidity

Volume and Volatility in the FX Market: Does it matter who you are?

The relationship between volume and volatility has received much attention in the literature on financial markets. However, due to the lack of data, few results have been presented for the foreign exchange (FX) market. Furthermore, most studies contain only aggregate series, and cannot distinguish between the impact of different participants or instruments. We study the impact of volume on volatility in the FX market using a unique data set of daily trading in the Swedish krona (SEK) market. The data set covers 95 percent of worldwide SEK trading, and is disaggregated on a number of reporting banks' buying and selling in five different instruments on a daily basis from 1995 until 2002. We find that volume in general show a positive correlation with volatility. However, the strength of the relationship depends on the instrument traded and the identity of the reporting bank. In particular, we find that trading tends to concentrate around the largest banks during periods of high volatility. These banks are probably also best informed. This is especially the case when volatility is high. We interpret this as evidence that heterogeneous expectations are important to an understanding of the volume- volatility relationship.Volume-volatility relation; microstructure; exchange rates

Volume and Volatility in the FX-Market: Does it matter who you are?

The relationship between volume and volatility has received much attention in the the literature of financial markets. However, due to the lack of data, few results have been presented for the foreign exchange market. Further, most studies contain only aggregate series, and can not distinguish between the impact of different instruments or participants.We study the impact of volume on volatility in the the FX-market using a unique data set of daily trading in the Swedish krona (SEK) market. The data set covers 95 per cent of worldwide SEK-trading, and is disaggregated on a number of reporting banks’ buying and selling in five different instruments on a daily basis over a period of nine years. We find that volume in general depict a positive correlation with volatility. However, the strength of the relationship depends on the instrument used and the identity of the reporting bank. In particular we find that it is the large Swedish banks that dominate the relationship. These banks are probably also the best informed banks. We interpret this is as evidence that heterogeneous expectations are important to understand the volume-volatility relationship.volume volatility relation, microstructure, exchange rates.

The Norwegian Height System NN1954 Revisited

Vertical reference systems based on national precise levelling networks have been realised in Europe since the 1860’s. The heights are related to gravity, which by convention may be measured values or amodel. The Norwegian Height System was adjusted in 1956 when the southern part of the country had been levelled once. Because of the lack of measured gravity, Clairaut’s formula for gravity was used in the orthometric correction. The intention was to establish an orthometric height system, but this was never tested or confirmed. In the literature the system is often referred to as orthometric, but some times as normal orthometric. This study shows that the Norwegian Height System was realised by a strongly deformed net due to lack of land uplift corrections. The derived heights are neither normal nor orthometric. When the land uplift is handled in a proper way, the heights are close to normal heights. The remaining small differences are shown to depend on the free air anomaly

Surgical resection of brain metastases: the prognostic value of the graded prognostic assessment score

There is a need for better predictors for short survival in patients with brain metastases undergoing open surgery. The graded prognostic assessment (GPA) has recently been developed to predict survival in patients with brain metastases. We explored the prognostic capabilities of GPA in a consecutive neurosurgical population of brain metastases. Secondarily, we evaluated if GPA scores can provide information on safety of the operation and postoperative functional outcome. We retrospectively included all adult (≥18 years) patients undergoing open surgery for brain metastases from 2004 through 2009 (n = 141). The population was grouped into GPA 0–1 (n = 22, 16%), GPA 1.5–2.5 (n = 90, 64%), GPA 3 (n = 19, 14%), and GPA 3.5–4 (n = 10, 7%) according to the prognostic indices. Median survival times were 6.3 months (range 0.8–23.7) in GPA 0–1, 7.8 months in GPA 1.5–2.5 (range 0.2–75.0), 14.0 months in GPA 3 (range 0.0–77.4), and 18.4 months in GPA 3.5–4 (range 0.1–63.7). This represents a significant difference between groups (P = 0.010). There were no associations between GPA and 30-day mortality (P = 0.871), 3-month mortality (P = 0.750), complications (P = 0.330) or change in Karnofsky Performance status postoperatively (P = 0.558). GPA scores hold prognostic properties in patients operated for brain metastases. However, GPA did not predict short-term mortality, limiting the clinical usefulness in a neurosurgical population. The prognostic indices cannot be used alone to decide if surgery is warranted on an individual basis, or to evaluate risks and benefits of surgery

On the possible existence of short-period g-mode instabilities powered by nuclear burning shells in post-AGB H-deficient (PG1159-type) stars

We present a pulsational stability analysis of hot post-AGB H-deficient pre-white dwarf stars with active He-burning shells. The stellar models employed are state-of-the-art equilibrium structures representative of PG1159 stars derived from the complete evolution of the progenitor stars. On the basis of fully nonadiabatic pulsation computations, we confirmed theoretical evidence for the existence of a separate PG1159 instability strip in the $\log T_{\rm eff} - \log g$ diagram characterized by short-period $g$-modes excited by the $\epsilon$-mechanism. This instability strip partially overlaps the already known GW Vir instability strip of intermediate/long period $g$-modes destabilized by the classical $\kappa$-mechanism acting on the partial ionization of C and/or O in the envelope of PG1159 stars. We found that PG1159 stars characterized by thick He-rich envelopes and located inside this overlapping region could exhibit both short and intermediate/long periods simultaneously. we study the particular case of VV 47, a pulsating planetary nebula nucleus that has been reported to exhibit a series of unusually short pulsation periods. We found that the long periods exhibited by VV 47 can be readily explained by the classical $\kappa$-mechanism, while the observed short-period branch below $\approx 300$ s could correspond to modes triggered by the He-burning shell through the $\epsilon$-mechanism, although more observational work is needed to confirm the reality of these short-period modes. Were the existence of short-period $g$-modes in this star convincingly confirmed by future observations, VV 47 could be the first known pulsating star in which both the $\kappa$-mechanism and the $\epsilon$-mechanism of mode driving are simultaneously operating.Comment: 9 pages, 5 figures, 2 tables. To be published in The Astrophysical Journa

Open-Label, Multi-Dose, Pilot Safety Study of Injection of OnabotulinumtoxinA Toward the Otic Ganglion for the Treatment of Intractable Chronic Cluster Headache

BACKGROUND: The otic ganglion (OG) provides parasympathetic innervation to the cerebral circulation and cranial structures and may be involved in the pathophysiology of trigeminal autonomic headaches. This structure has never been targeted in any headache disorder. OBJECTIVE: To investigate the safety of injecting onabotulinumtoxin A (BTA) toward the OG in 10 patients with intractable chronic cluster headache and to collect efficacy data. METHODS: A total of 10 patients with chronic cluster headache were enrolled in this open-label, multi-dose pilot safety study. All patients were recruited and treated on an out-patient basis at St Olav's University Hospital (Norway). In 5 patients each, the OG was the injection target with 12.5 IU of BTA or 25 IU, respectively. The primary outcome measure was adverse events (AEs) and the main secondary outcome was the number of attacks per week measured at baseline and in the second month following injection. RESULTS: For the primary endpoint, we analyzed data for all 10 patients. There were a total of 17 AEs in 6 of the 10 patients. All AEs were considered mild and disappeared by the end of follow-up. The median number of attacks per week at baseline was 17.0 [7.8 to 25.8] vs 14.0 [7.3 to 20.0] in the second month following injection; difference: 3 (95%CI: -0.3 to 7.9), P = .063. CONCLUSIONS: Injection with BTA toward the OG appears to be safe. We did not find a statistically significant reduction in the number of attacks per week at month 2 after injection compared to the baseline. This study suggests that the OG is not an important target for the treatment of chronic cluster headache. A future study employing more precise targeting of the OG may be indicated