Pervasiveness of the IQ Rise: A Cross-Temporal Meta-Analysis

Background: Generational IQ gains in the general population (termed the Flynn effect) show an erratic pattern across different nations as well as across different domains of intelligence (fluid vs crystallized). Gains of fluid intelligence in different countries have been subject to extensive research, but less attention was directed towards gains of crystallized intelligence, probably due to evidence from the Anglo-American sphere suggesting only slight gains on this measure. In the present study, development of crystallized intelligence in the German speaking general population is assessed. Methodology/Principal Findings: To investigate whether IQ gains for crystallized intelligence are in progress in Germanspeaking countries, two independent meta-analyses were performed. By means of a cited reference search in ISI Web of Science, all studies citing test manuals and review articles of two widely-used salient measures of crystallized intelligence were obtained. Additionally, the electronic database for German academic theses was searched to identify unpublished studies employing these tests. All studies reporting participants mean IQ or raw scores of at least one of the two measures were included in the present analyses, yielding over 500 studies (.1,000 samples;.45,000 individuals). We found a significant positive association between years of test performance and intelligence (1971–2007) amounting to about 3.5 IQ points per decade. Conclusions/Significance: This study clearly demonstrates that crystallized IQ gains are substantial and of comparabl

The Newcomb-Benford Law in Its Relation to Some Common Distributions

An often reported, but nevertheless persistently striking observation, formalized as the Newcomb-Benford law (NBL), is that the frequencies with which the leading digits of numbers occur in a large variety of data are far away from being uniform. Most spectacular seems to be the fact that in many data the leading digit 1 occurs in nearly one third of all cases. Explanations for this uneven distribution of the leading digits were, among others, scale- and base-invariance. Little attention, however, found the interrelation between the distribution of the significant digits and the distribution of the observed variable. It is shown here by simulation that long right-tailed distributions of a random variable are compatible with the NBL, and that for distributions of the ratio of two random variables the fit generally improves. Distributions not putting most mass on small values of the random variable (e.g. symmetric distributions) fail to fit. Hence, the validity of the NBL needs the predominance of small values and, when thinking of real-world data, a majority of small entities. Analyses of data on stock prices, the areas and numbers of inhabitants of countries, and the starting page numbers of papers from a bibliography sustain this conclusion. In all, these findings may help to understand the mechanisms behind the NBL and the conditions needed for its validity. That this law is not only of scientific interest per se, but that, in addition, it has also substantial implications can be seen from those fields where it was suggested to be put into practice. These fields reach from the detection of irregularities in data (e.g. economic fraud) to optimizing the architecture of computers regarding number representation, storage, and round-off errors

Seven common distributions of random variables.

<p>Uniform distribution, exponential distributions with and , half-normal distributions with and , right-truncated normal distribution with and , normal distribution with and , chi-square distributions with , , and , log-normal distributions with and , and , and and .</p

Normal distribution and ratio of two normals.

<p>Normal distribution and ratio of two normals.</p

Uniform distribution and ratio of two uniforms.

<p>Uniform distribution and ratio of two uniforms.</p

Three distributions of the ratio of two random variables.

<p>Ratio distribution of two uniforms <i>U</i>(0,1), ratio distribution of two exponentials with same , ratio distribution of two chi-squares (<i>F</i>-distribution) with , , and .</p

Right-truncated normal distribution and ratio of two right-truncated normals.

<p>Right-truncated normal distribution and ratio of two right-truncated normals.</p

Chi-square distribution and ratio of two chi-squares (<i>F</i>-distribution).

<p>Chi-square distribution and ratio of two chi-squares (<i>F</i>-distribution).</p

Schulleistung in Deutsch und ethnische Zusammensetzung der Schülerpopulation

In der vorliegenden Studie wurde sowohl der Einfluss des Schulanteils an Kindern mit einer anderen Muttersprache als Deutsch auf die Sprachleistung (Leseverständnis, Wortschatz und Rechtschreibung) deutschsprachiger Kinder als auch jener des Anteils deutschsprachiger Kinder auf die Sprachleistung von Kindern mit Migrationshintergrund untersucht. Es nahmen 211 Kinder aus der vierten Grundschulstufe, 84 mit Deutsch als Muttersprache (39.8%) und 127 mit einer anderen Muttersprache als Deutsch (60.2%), teil. Kognitive Grundfähigkeiten und der sozioökonomische Hintergrund wurden miterhoben. Die mehrebenenanalytische Auswertung zeigte Effekte der kognitiven Grundfähigkeiten und des sozioökonomischen Hintergrundes auf die Sprachleistung. Die ethnische Zusammensetzung der Schule war nicht bedeutsam. Bei Kindern mit Migrationshintergrund erwies sich der Zeitpunkt des Spracherwerbs als wichtig für die Sprachleistung. Ein möglichst frühzeitiger Erwerb der Sprache des Einwanderungslandes ist daher dringend zu empfehlen. (Autor/inn/enref.)Series: Discussion Paper Series / Center for Empirical Research Method