State IQ and suicide rates in the United States

Previous findings pertaining to the direction (positive or negative) of the ecological correlation between intelligence and suicide rates in the USA have been conflicting. Using novel state IQ estimates, derived from the Scholastic Assessment Test, the American College Test, these tests combined, or the National Assessment of Educational Progress state scores, these estimates were not consistently associated to state suicide rates. Whereas ACT-derived state IQ was significantly positively correlated with suicide rates, the correlation with composite ACT-SAT-derived state IQ was significantly negative and with both SAT-derived and NAEP-derived state IQ also negative but not significant. Validity checks pointed to possible methodological problems with the state IQ estimates. Currently available estimates of state IQ, therefore, seem not appropriate to resolve the question of the direction of the ecological correlation of intelligence and suicide mortality across the USA.     

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.     

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.     

National intelligence and suicide rate across Europe: an alternative test using educational attainment data

National mean scores on a historical knowledge test (taken as a proxy for intelligence), stemming from representative samples of male (and female) 9th-grade school students from 26 European countries in a 1999 report by Wilberg and Lynn, were significantly positively associated with the national male (and female) suicide rates, independent of the general quality-of-living conditions in these countries. This finding replicates previous evidence from cross-national studies (by Lester and by Voracek), of a correspondence of higher national IQ to higher suicide rates, with an alternative measure of national IQ that is independent of the national IQ estimates recently published by Lynn and Vanhanen which have been used in prior studies.     

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.     

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.     

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.     

State preferences for the ACT versus SAT complicates inferences about SAT-derived state IQ estimates: A comment on Kanazawa (2006)

Kanazawa [Kanazawa, S. (2006). IQ and the wealth of states. Intelligence, 34, 593–600.] offered estimates of state IQ derived from SAT data. The purpose of this commentary is to argue that state preferences for the use of the ACT versus the SAT create biased estimates of SAT-derived state IQ for states where the ACT is more frequently used than the SAT. This error can be reduced by using both ACT and SAT data to estimate state IQ. An IQ estimate based on a ACT-SAT composite and a NAEP-derived state IQ estimate were compared as predictors of three wealth variables. Both IQ estimates cause one to conclude that states with higher mean IQ have larger gross state product per capita, higher median incomes, and a lower percentage of their population in poverty.     

States' public welfare expenditures as predictors of state suicide rates

This exploratory multiple-regression study took its cue from social integration theory to examine the relative importance of state per capita expenditures for public welfare in predicting state suicide rates when controlling for the effects of state divorce rates, state population change rates, and the percentage of persons with annual incomes between $10,000 and $19,999. While the four variables together accounted for .73 of the explained variance in state suicide rates, the effects of state per capita expenditures for public welfare were not very important when those of the other variables were taken into account. This, however, does not mean that state per capita expenditures for public welfare are inconsequential with respect to state suicide rates, inasmuch as they were inversely related to each of the other three independent variables, each of which was positively related to state suicide rates. This means that state per capita expenditures are indirectly related to suicide--in a negative direction. The implications of the findings for policy and suicide prevention are briefly discussed.     

National estimates of IQ and suicide and homicide rates

Nations with high estimated mean IQ scores had higher suicide rates and lower homicide rates after control for gross domestic product was introduced, significantly in 1970 but not in 1980.     

Evidence for a positive ecological correlation of regional intelligence and suicide mortality in the United States during the early 20th century

Several contemporary cross-national and intranational geographic studies have reported positive ecological (group-level) associations of intelligence and suicide mortality. These findings are consistent with facts from suicide research and with an evolutionary view of suicidal behavior. The present research extended these accounts cross-temporally. Analysis of E. L. Thorndike's state-level personal quality scores and standardized birth rates of eminent persons, taken as proxy variables for regional intelligence, along with historical state suicide rates (1913-1924 and 1928-1932) showed that intelligence and suicide mortality across the U.S.A. were already clearly positively related during the early 20th century, suggesting time stability of the effect. Within the U.S.A., the effect is possibly due to state differences in the ethnic composition, which correspond to both suicide rates and intelligence proxies. It is argued that the most parsimonious interpretation of these ecological findings remains that they indeed reflect individual-level effects, that a positive link between intelligence and suicide is entirely compatible with positive overall links between intelligence and health and longevity, and that the ultimate explanative background for the positive link between intelligence and suicide may be provided through the framework of Rushton's differential K theory.     

Estimating state IQ: Measurement challenges and preliminary correlates

The purpose of this study is threefold. First, an estimate of state IQ is derived and its strengths and limitations are considered. To that end, an indicator of downward bias in estimating state IQ is provided. Two preliminary causal models are offered that predict state IQ. These models were found to be highly predictive of state IQ, yielding multiple R's of 0.83 and 0.89. Second, the extent to which state IQ predicts state outcome variables (e.g., gross state product, health, violent crime, and government effectiveness) is estimated. State IQ shows positive correlations with gross state product, health, and government effectiveness and negative correlations with violent crime. These results are consistent with the extent to which IQ predicts outcomes at the level of the individual. Third, a research agenda is provided for improving estimates of state IQ, identifying factors that cause differences in state IQ, and delineating the role of IQ in predicting important variables.     

The impact of epidemic, war, prohibition and media on suicide: United States, 1910-1920.

The paper utilizes a natural experiment approach to estimate the impact of exogenous social and political events on suicide behavior in the United States between 1910 and 1920. The study is concerned with determining the impact of World War I, the great Influenza Epidemic, and the prohibition experiment on suicide. Estimating the monthly population in the United States registration area from 1910 to 1920, monthly suicide and mortality rates are computed. A time-series model is postulated, and second-order autoregressive estimates are used to determine the impact of the independent variables in the model. It is concluded that World War I did not influence suicide; the Great Influenza Epidemic caused it to increase; and the continuing decline in alcohol consumption between 1910 and 1920 depressed national suicide rates. Further individual-level aggregate studies are needed to confirm the findings of the study.     

A state level investigation of the associations among intellectual capital, religiosity and reproductive health

The current study examines the degree to which state intellectual capital, state religiosity and reproductive health form a meaningful nexus of ecological relations. Though the specific magnitude of effects vary across outcomes, results from hierarchical regression analyses were consistent with the hypothesized path model indicating that a state's intellectual capital (as indicated by average state IQ and graduation rates at various levels) has a positive overall effect on state reproductive health statistics, whereas state religiosity generally has a negative impact. Specifically, both IQ and education were positively associated with breastfeeding rates, immunization rates, and rates of mammography screening, and negatively associated with teen fertility rates and infant mortality rates. Additionally, results confirm that education rates partially mediate the influence of IQ onto religiosity, and both education and religiosity partially or fully mediate the relation between IQ and state health (depending on specific outcome measure). The current results are consistent with a growing interdisciplinary literature establishing that individual, state and national well-being is substantially related to general mental ability and its covariates.     

Associations between climate and IQ in the United States of America

Relations between average temperature of each of the 48 contiguous states and estimates of state IQ were inspected. Additional state variables were controlled in the correlational analyses, namely gross state product, percent Hispanic, Black, and Asian in the state population, and the pupil-to-teacher ratio for each state. A significant correlation between average temperature and state IQ was found (r = -.70, p < .001). Possible explanations are discussed.     

Accidental and unspecified deaths among prisoners as disguised suicides.

Analysis of 1987 data from the US Department of Justice for prisoners under the jurisdiction of state and federal correctional authorities indicated that suicide rates were not negatively correlated with accidental or unspecified death rates. These findings do not provide evidence of disguised suicides among prisoners. Possible explanations for high rates of unspecified death among prisoners are presented.     

An application of the empirical Bayes approach to directly adjusted rates: a note on suicide mapping in California

A simple, reliable, and comparable measure for suicide mapping and other health problems is needed. Because standardized mortality ratios (SMRs) may not indicate the relative meaning of their magnitudes when compared with one another, and statistical significance levels of tests for SMRs overlook the areas that have small populations, neither of these approaches provides a satisfactory index. The results using directly adjusted rates can be ordered directly according to their magnitudes. However, because of the lack of reliable estimates of local age-specific rates, the usefulness of directly adjusted rates in mapping suicide is also limited. To extend the usefulness of directly adjusted rates, an empirical Bayes approach whereby information from other areas is borrowed to improve the precision of the estimates of local age-specific rates in calculating directly adjusted rates--especially in the areas with small population sizes--is proposed. When an empirical Bayes approach was applied to the 1983 suicide data for California counties, a more reasonable conclusion than could be obtained by using directly adjusted rates was reached.     

Firearm legislation and statewide suicide rates: The moderating role of household firearm ownership levels

Firearm legislation is associated with statewide suicide rates; however, prior research has often relied upon older data and categorical legislative grades while also failing to consider the nuanced role of firearm ownership. Therefore, the robust literature base on legislation and suicide has not directly examined regarding the extent to which the value of legislation hinges upon the rate of firearm ownership in a given state. The current study examined 2015 US statewide firearm legislation strength scores from Giffords Law Center to Prevent Gun Violence and 2016 statewide suicide rates from the Centers for Disease Control and Prevention. Firearm legislation strength was inversely associated with statewide overall and firearm suicide rates, but not with non‐firearm suicide rates. Firearm ownership rates moderated the association between firearm legislation strength and statewide overall suicide rates. Specifically, firearm legislation strength was inversely associated with statewide overall suicide rates at mean and high levels of firearm ownership. Findings support the potential utility of firearm legislation as part of a national effort to decrease US suicide deaths, particularly in areas with higher firearm ownership rates.     

Older Adults: The Next Suicide Epidemic?

Suicide rates historically and currently are highest by age among those over the age of 65. Predictions of markedly higher rates for future older adults have been advanced. Possible alternative factors that might produce lower risk among future elderly Americans are presented and it is argued that future trends are uncertain. Predictions of elderly suicide are made based on an assumption of stable rather than changing rates. Constant rates produce estimates of more than twice the current number of suicides and a proportionate increase in the number of suicides from one in five for the 1980s to one in three by the year 2030. The elderly are and likely will be a group with high suicide risk. Immediate efforts to lower elderly suicide risk and avert high future rates are recommended.     

The Association Between Gun Ownership and Statewide Overall Suicide Rates

An extensive body of research has demonstrated an association between gun ownership and suicide that extends beyond the effects of a range of covariates. We aimed to expand on extant research by examining the extent to which gun ownership predicts statewide overall suicide rates beyond the effects of demographic, geographic, religious, psychopathological, and suicide‐related variables. By extending the list of covariates utilized, considering those covariates simultaneously, and using more recent data, we sought to present a more stringent test. Gun ownership predicted statewide overall suicide rates, with the full model accounting for more than 92% of the variance in statewide suicide rates. The correlation between firearm suicide rates and the overall suicide rate was significantly stronger than the correlation between nonfirearm suicide rates and the overall suicide rate. These findings support the notion that access to and familiarity with firearms serves as a robust risk factor for suicide. Therefore, means safety efforts aimed at reducing accessibility and increasing safe storage of firearms would likely have a dramatic impact on statewide overall suicide rates.