Analyse von qualitativen abhängigen Variablen

Um die strukturellen Beziehungen zwischen mehreren Größen aufdecken oder entsprechende Hypothesen testen zu können, bedarf es multivariater Analysemethoden, mit denen man eine Vielzahl von Variablen unter Berücksichtigung von (zufälligen) Fehlereinflüssen bzw. Störgrößen simultan betrachten kann. Eine Gruppe von Modellen, die speziell auf die Analyse qualitativer abhängiger Variablen zugeschnitten sind, wird in dem Beitrag vorgestellt. Dabei handelt es sich um Regressionsmodelle, mit denen sich mehrdimensionale Kontingenztabellen analysieren lassen. (pmb

Time Series Event Forecasting in Consumer Electronic Markets using Random Forests

Consumers are price-sensitive and opportunistic about the place of purchase when buying electronic goods. However, services that advise customers on their purchase time decisions for those products are missing. Given the objective to provide a binary signal to customers to either wait or purchase immediately, classification algorithms are a direct methodological choice. Approaches like random forests allow for the derivation of a probability and class prediction but are usually not used in time series contexts. This is due to missing or time-invariant regressors and unclear prediction settings. We show how classification methods can be used to generate reliable predictions of price events and analyze if they are subject to common market dependencies. Pooling univariate random forests and enhancing them with multivariate features shows that our approach generates stable and valuable recommendations. Because dependency structures between products are transferable, multivariate forecasting increases accuracy and issues recommendations where univariate approaches fail

Beispiel für die Evolution der Synthese eines Entwicklungsproduktes: Herstellung des als 5 HT2C/2B-Receptor-Antagonisten wirksamen Indolo-naphthyridin-Derivates SDZ SER-082 in enantiomerenreiner Form

cis-4,5,7a,8,9,10,11,11a-Octahydro-7H-10-methylindolo[1,7-bc][2,6]naphthyridine (rac-4) (SDZ SER-082) is a selective and potent 5-HT2C/2B receptor antagonist, exerting weak affinity towards the 5-HT2A receptor site. The compound 4 was found to be a potential development candidate in several CNS indications. The key step in the initial synthesis was the photocyclization of the indolyl tetrahydropyridino-carbamic acid ethyl ester 1 to afford the cis/trans-naphthyridine 2/3. This process turned out to be inefficient for a scale-up. Three alternative synthetic routes A, B and C are discussed: The 'Imino-Diels-Alder' reaction applying indoline/formaldehyde/cyclopentadiene (route A) and the intramolecular Heck cyclization of 7-bromo-2,3-dihydro-1-[(1,2,5,6-tetrahydro-1-methyl-4-pyridyl)-carbonyl]-1H -indole (10) (route B) were surpassed in their synthetic efficiency by the Friedel-Crafts cyclization of 4-(2,3-dihydroindole-1-carbonyl)-1-methylpiperidin-3-one (16) (route C), followed by reduction to give rise to the racemic naphthyridine rac-4. It was subjected to resolution by applying a kg scale repetitive chromatography on a chiral stationary phase to give (+)-(7aS,11aR)-4 in over 90% yield and 99.9% enantiomeric purity