Exponential fitting of suicide rate and national intelligence estimates

Positive ecological (group-level) associations of Lynn and Vanhanen's 2002 national intelligence (IQ) estimates with the suicide rates of men and women across 85 countries and with the suicide rates of the male, female, and total elderly population across 48 Eurasian countries reported recently is extended by the finding that this ecological association was notedly better accounted for by exponential fitting than by linear fitting. This evidence implies that the effect of a shift in the national IQ on the suicide rate is proportional, not absolute. As a rule of thumb, a 5-point shift in national IQ roughly corresponds to a 50% change in the national suicide rate.     

Regional intelligence and suicide rate: new data for Australia and a synthesis of research

Previous research has shown for the most part positive correlations between intelligence and suicide prevalence on the national level. However, this study found proxies for regional intelligence in Australia (international average domain scores from the PISA 2000 study) to be significantly negatively correlated with the total, male, and female suicide rates of the different administrative divisions of Australia, and this finding was independent of regional wealth. A research synthesis of the current results and those from similar studies of other countries (positive correlations for Austria, Belarus, The British Isles, Denmark, and The Netherlands; inconclusive findings for France, Germany, and the USA) was conducted. This synthesis of research findings showed that positive ecological correlations of intelligence with suicide rate were more likely observed for nations with higher suicide rates and poorer general living conditions, whereas there was no relation with national IQ.     

Cross-national social ecology of intelligence and suicide prevalence: integration, refinement, and update of studies

This study integrates, refines, and updates previous findings pertaining to positive ecologic (population-level) associations between intelligence and suicide prevalence across nations by using corrected and revised national IQ estimates and, further, a quality-of-human-conditions index, both recently published by Lynn and Vanhanen. Across a global 85-nation sample of sex-specific total suicide rates and a Eurasian 48-nation sample of sex-specific elderly suicide rates, these were positively associated with updated national IQ estimates. The associations were stronger for the general population than for elderly persons, independent of the quality of human conditions, and notedly stronger in exponential fitting of suicide rates with national IQ than in linear fitting, thereby indicating that shifts or differences in national IQ correspond to proportional, not absolute, changes in suicide rates. Implications of these findings and the question of generalizability of such associations to the individual level are discussed.     

National differences in intelligence and population rates of suicidal ideation, suicide plans, and attempted suicide

Population rates of suicidal ideation, suicide plans or attempted suicide from three independent multinational epidemiological surveys (the WHO/EURO and WHO SUPRE-MISS studies and a third one) were not significantly associated with national IQ figures. This result conflicts with previous evidence from cross-national studies (by Lester and by Voracek) of a positive ecological correlation between level of national intelligence and rates of completed suicide. Across nations, the indicators for the prevalence of suicidal behavior also lacked close correspondence with suicide rates, which may be due to the higher unreliability of assessing covert suicidal behavior (suicide ideas, thoughts, plans, and, to a lesser extent, also suicide attempts) as compared to suicidal behavior that is indisputably overt (completed suicide). Several alternative explanations for the current nil findings are also discussed.     

A systematic literature review of the average IQ of sub-Saharan Africans

On the basis of several reviews of the literature, Lynn [Lynn, R., (2006). Race differences in intelligence: An evolutionary analysis. Augusta, GA: Washington Summit Publishers.] and Lynn and Vanhanen [Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Augusta, GA: Washington Summit Publishers.] concluded that the average IQ of the Black population of sub-Saharan Africa lies below 70. In this paper, the authors systematically review published empirical data on the performance of Africans on the following IQ tests: Draw-A-Man (DAM) test, Kaufman-Assessment Battery for Children (K-ABC), the Wechsler scales (WAIS & WISC), and several other IQ tests (but not the Raven's tests). Inclusion and exclusion criteria are explicitly discussed. Results show that average IQ of Africans on these tests is approximately 82 when compared to UK norms. We provide estimates of the average IQ per country and estimates on the basis of alternative inclusion criteria. Our estimate of average IQ converges with the finding that national IQs of sub-Saharan African countries as predicted from several international studies of student achievement are around 82. It is suggested that this estimate should be considered in light of the Flynn Effect. It is concluded that more psychometric studies are needed to address the issue of measurement bias of western IQ tests for Africans.     

National IQs predict educational attainment in math,reading and science across 56 nations

The results of the 2006 PISA (Program for International Student Assessment) study of reading comprehension, mathematical ability, and science understanding administered to 15 year olds in 56 countries [OECD (2007). PISA 2006: Science Competencies for Tomorrow's World. Paris: OECD.] are examined to assess the predictive validity of the national IQs presented by Lynn and Vanhanen [Lynn, R., & Vanhanen, T. (2002). IQ and the wealth of nations. Westport, CT: Praeger., Lynn, R., & Vanhanen, T. (2006). IQ and global inequality. Augusta, GA: Washington Summit Books.], and to assess the contributions of national differences in IQ and educational variables to national differences in educational attainment. It was found that national scores in reading comprehension, mathematical ability, and science understanding are correlated with Lynn & Vanhanen (L & V) national IQs at 0.84; corrected for attenuation, 0.935. This establishes the high validity of Lynn & Vanhanen national IQs. The contribution of national differences in IQ and education variables to national differences in educational attainment obtained in the 2006 PISA 56 nation study showed that the predictive validity of IQ alone was 0.84, and that national IQs together with one economic and two education variables had the validity 0.90 in predicting PISA 2006 results.     

Association of suicide rates for elderly age bands with gender equality

A lower sex ratio (male to female) of elderly suicide rates in several Asian countries have been attributed to gender inequality on several parameters. The association of two proxy measures of gender equality (value of the gender empowerment measure and the gender-related development index) and the male to female sex ratio of suicide rates in the age bands 65-74 yr. and 75+ yr. was examined using multiple linear regression. The two proxy measures of gender equality did not account for significant variance in the male to female sex ratio of suicide rates in the age bands 65-74 yr. and 75+ yr. Association of gender equality with the male to female sex ratio of suicide rates requires further clarification in both cross-sectional studies across different countries and longitudinal studies within individual countries for all age bands. Such studies should, in addition to the GEM and the GDI, include other measures of gender equality including sex differences in educational attainment, income, poverty, housing, employment, access to healthcare and social welfare services, and urbanisation.     

Modernization and the Male–Female Suicide Ratio in India 1967–1997: Divergence or Convergence?

The traditional view that modernization is likely to increase male vulnerability to suicide while protecting females from such self-destruction was offered by Durkheim (1951). This implies a theory of divergence of suicide rates such that the male-female suicide ratio should increase with modernization. Contemporary researchers have questioned whether modernization has had such an impact. We conducted a time series analysis of male and female suicide data to determine the impact on the suicide ratio for India for the years 1967 to 1997. We developed a modernization index comprised of urbanization, female literacy, and female work participation rates. Moreover, to improve methodological efficacy, we controlled for the passage of time. However, we found that there is no significant relationship between modernization and the male-female suicide ratio. Our conclusion is that using national male-female suicide ratios to determine modernization effects may mask significant regional gender and age differences, particularly in developing countries such as India.     

National differences in intelligence,crime, income,and skin color

National differences in murder, rape, and serious assault were examined in 113 countries in relation to national IQ, income, skin color, birth rate, life expectancy, infant mortality, and HIV/AIDS. Data were collated from the 1993–1996 International Crime Statistics published by INTERPOL. Violent crime was found to be lower in countries with higher IQs, higher life expectancies, lighter skin color, and lower rates of HIV/AIDS, although not with higher national incomes or higher rates of infant mortality. A principal components analysis found the first general factor accounted for 52% of the variance. Moreover, the correlations were significantly higher with skin color, a more biologically influenced variable, than with measures of national income, a more culturally influenced variable. When the 19 sub-Saharan African countries were excluded from analysis the crime/IQ relation held but the crime/skin color relation did not.     

Social indicators as indexes of neuroticism and extraversion

Lynn and Hampson (1975) and recently Lester (2000) suggested that national level of extraversion (E) and neuroticism (N) could be assessed by using certain national indicators like suicide and divorce rates. In this study, Lynn and Hampson’s (1975) and Lester’s (2000) models were assessed by using 1990s data. Although Lynn and Hampson’s original N and E factors correlated with EPQ N (r=0.48) and E (r=0.60) scores as hypothesised, the factor structure did not recur in the 1990s data. Factor analysis supported Lester’s (2000) model of N and E. However, the factor loadings for EPQ N and E were rather modest (0.49 for N and 0.36 for E). It was concluded that more research with larger datasets and new social indicators are needed before social indicators could replace the EPQ in comparisons of national characteristics of nations.     

The Big Ten Student Suicide Study: A 10-Year Study of Suicides on Midwestern University Campuses

The Big Ten Student Suicide Study was undertaken from 1980–1990 to determine the suicide rates on Big Ten University campuses. The study design attempted to address many of the statistical and epidemiological flaws identified in previous studies of campus student suicides. The 10-year study collected demographic and correlational data on 261 suicides of registered students at 12 midwestern campuses. The largest number of suicides for both males and females were in the 20–24-year-old age group (46%), and amongst graduate students (32%). The overall student suicide rate of 7.5/100,000 is one half of the computed national suicide rate (15.0/100,000) for a matched sample by age, gender, and race. Despite the overall lower suicide rate, the analyses revealed that students 25 and over have a significantly higher risk than younger students. Although women have rates roughly half those of men throughout their undergraduate years, graduate women have rates not significantly different from their male counterparts (graduate women 9.1/100,000 and graduate men 11.6/100,000).     

Rate, relative risk, and method of suicide by students at 4-year colleges and universities in the United States, 2004-2005 through 2008-2009

A total of 622 suicides were reported among students attending 645 distinct campuses from 2004-2005 through 2008-2009. Adjusting for gender in the population at risk of 14.9 million student-years and for the source of these data, the student suicide rate of 7.0 was significantly and substantially lower than for a matched national sample. Suicide rates by firearm were significantly and substantially lower for both female and male students. Hanging was significantly and substantially lower for male students, less prominently so for female students. It is principally the ninefold decrease in the availability of firearms on campuses (vs. homes) and secondarily other features of the campus environment that are the bases for lower student suicide rates.     

A thematic comparison of suicide notes drawn from Northern Ireland and the United States

Suicide is a global concern hence cross-cultural research ought to be central to national suicide prevention strategies. This study sought to investigate suicide notes drawn from Northern Ireland and the United States as these countries have broadly similar suicide rates but markedly different cultures. A theoretical-conceptual analysis of sixty suicide notes drawn from these countries, matched for age and sex, was undertaken based on a thematic model of suicide developed by Leenaars (1996) across countries. The results suggested that there were more psychological commonalities than differences. Two differences emerged which suggested that aspects of the interpersonal components may be more salient in Northern Irish rather than American suicides. It is argued that more wide-ranging cross-cultural studies are required to enhance our ability to identify and predict those most at risk from suicide.     

A thematic comparison of suicide notes drawn from Northern Ireland and the United States

Suicide is a global concern hence cross-cultural research ought to be central to national suicide prevention strategies. This study sought to investigate suicide notes drawn from Northern Ireland and the United States as these countries have broadly similar suicide rates but markedly different cultures. A theoretical-conceptual analysis of sixty suicide notes drawn from these countries, matched for age and sex, was undertaken based on a thematic model of suicide developed by Leenaars (1996) across countries. The results suggested that there were more psychological commonalities than differences. Two differences emerged which suggested that aspects of the interpersonal components may be more salient in Northern Irish rather than American suicides. It is argued that more wide-ranging cross-cultural studies are required to enhance our ability to identify and predict those most at risk from suicide.     

IQ and the wealth of states

In IQ and the Wealth of Nations (2002), Lynn and Vanhanen estimate the mean IQs of 185 nations and demonstrate that national IQs strongly correlate with the macroeconomic performance of the nations, explaining about half of the variance in GDP per capita. I seek to replicate Lynn and Vanhanen's results across states within the United States. I first estimate “state IQs” from the SAT data, and show that the state IQs correlate moderately with the economic performance of the states, explaining about a quarter of the variance in GSP (gross state product) per capita.     

Relationship of IQ to suicide and homicide rate: an international perspective

IQs were correlated with the z score of suicide rate minus z score of homicide rate using nine regions of the world--established market economies, formerly socialized Europe, India, China, other Asian nations, Sub-Saharan Africa, Latin America/Caribbean, Middle East Crescent, and the USA. Correlations were .85 and .83 with crude rates and age-adjusted rates, respectively. The homicide findings are consistent with previous research in individual countries showing that less intelligent persons commit homicide more often. However, the present findings of a positive correlation between IQ and suicide rates are the opposite of what has been found in the more definitive studies within countries. Explanations for the apparent paradox and for the findings more generally were offered.     

Temporal variation in Irish suicide rates

Using Irish suicide data for the period 1990-1998, the independent effects of month and day adjusting for age, gender, and calendar year effects and distinguishing between holiday and working Mondays were assessed. The male suicide rate was significantly higher on working Mondays (+31%) and Saturdays (+14%), and during April, June, and August (+17%), after adjustment for the other variables. In contrast, female suicide rates were higher only in August (+35%) and exhibited no day effect. Teenage men had a greater elevation of risk on Saturdays, Sundays, and both working and holiday Mondays than any other group. The study findings should be taken into account in the planning of specialized health care services and helplines for suicidal people. Furthermore, the findings provide support for Gabennesch's (1988) broken promise theory and the relationship between dysfunctions of the serotonergic system and suicidal behavior.     

Changing age patterns of U.S. male and female suicide rates, 1934-1983

Changes in the age patterns of U.S. male and female suicide rates from 1934 to 1983 are examined, using official suicide data. Among whites, the age patterns of male and female suicide rates have become less concordant since about 1960. In contrast, the age patterns of nonwhite male and female suicide rates have become more concordant since the mid-1950s. A review of sociological theories of suicide identifies problems in accounting for such changes--problems stemming in part from what has been a theoretical emphasis on cross-sectional relations.     

The Change in Suicide Rates between 2002 and 2011 in China

Chinese suicide rates have been reported in various studies in the past two decades, but few of them were based on national data. The most recent mortality data (2002–2011) provided by the China Ministry of Health and the detailed census data provided by the National Population Census were used in this study. We calculated the age‐, gender‐, and region‐specific suicide rates and their trends in the past 10 years between 2002 and 2011. The overall suicide rates in China decreased during the study period. The rural/urban ratio of the suicide rates has been significantly reduced from the ratio in the 1990s, and male suicide rates have exceeded those of females. Age was positively associated with suicide rates without the two peaks found in the suicide rates over 20 years ago. The Chinese suicide rates have significantly declined in the past decade, with withering of the unique suicide rate patterns previously found in Chinese suicides about 20 years ago.