Sot. .%I. Med. Vol. 29. No. I I. pp. 1249-1252. 1989 Prmted m Great Bntam. All rights reserved

0277-9536 89 53.00 + 0.00 Copyright p 1989 Pergamon Press plc

NATIONAL SUICIDE AND HOMICIDE RATES: CORRELATES VERSUS PREDICTORS

DAVID LESTER

Psychology Program, Richard Stockton State College. Pomona, NJ 08240. U.S.A.

Abstract-The present study explored correlates of national suicide and homicide rates in a sample of industrialized nations. A large set of social variables was factor-analyzed and the factors were correlated with both suicide and homicide rates and with changes in these rates. Different social variables were found to correlate with rates of suicide than with rates of homicide. and different variables correlated with current rates of personal violence than with changes in these rates.

Key naords-suicide, homicide. social correlates

INTRODUCTION

Two powerful sociological theories have been used to explain differences in the suicide and homicide rates of the nations of the world. Durkheim [I] proposed that suicide rates would be higher in societies where social integration was either very strong (leading to altruistic suicide) or very weak (leading to egoistic suicide) and where social regulation was either very strong (leading to fatalistic suicide) or very weak (leading to anemic suicide).

Henry and Short [2] argued that societies where external restraints and pressures on the citizens were strong would have higher rates of homicide and lower rates of suicide. whereas societies where external restraints and pressures on the citizens were weak would have lower rates of homicide and higher rates of suicide.

These two theories have stimulated many predic- tions. For example. nations with high rates of divorce should have high rates of suicide (because a higher rate of divorce implies a lower level of social integra- tion), a prediction confirmed by Stack [3]. Or societies with totalitarian rule should have higher rates of homicide and lower rates of suicide because a higher level of totalitarianism provides a clearer external source to blame for personal unhappiness, a predic- tion confirmed by Lester [4].

Indeed. a large number of cross-national studies have correlated various social variables with national rates of suicide and homicide. Each study highlights one or two significant correlates. Stack [5] focused on immigration, Lester [6] on national .indices of anxiety and extraversion. Breault and Barkey [7] on religiosity, and Ellner [8] on industrialization.

The purpose of the present study was to conduct one single study to explore the association of a large number of social variables with suicide and homicide rates. The present study identified clusters of social variables using factor analysis and then correlated these factors with rates of suicide and homicide.

There is a disagreement between researchers as to whether factor analysis or multiple regression is the better technique for studying the present problem. The disadvantage of multiple regression is that it picks out the variable with the highest correlation as the most critical variable, even though this correla-

tion may not be significantly higher than the next largest correlation. Factor-analysis, in contrast. groups all highly correlated variables together rather than picking that variable with the highest correlation as the critical variable. Once factors have been iden- tified, these factors can be used as independent variables in a multiple regression.

Sainsbury et al. [9] explored which social variables could predict changes in national suicide rates. Sains- bury et al. found that the proportion of young people and the divorce rate, for example, were positively associated with changes in the suicide rate.

A second purpose of the present study. there- fore, was to explore correlates of changes in rates of suicide and homicide, again using the technique of factor analysis to identify clusters of related social variables.

Two research strategies have been used for cross- national studies, to use data for all available nations (typically providing sample sizes of 35-50) and studies on more limited groups of nations. Stack [5], for example, studied the relationship between immigration rates and suicide rates in 34 nations, while Sainsbury et al. [9] limited their sample to 18 European nations. The present study focused on a sample of 18 industrialized nations first used by Lynn [IO] in his cross-national studies and subsequently employed by Lester in his research (e.g. [I I]).

Finally, previous research has usually restricted itself to the study of suicide rates, despite the fact that Henry and Short’s [2] theory of suicide viewed homi- cide as an opposed behavior. Social conditions that increase the rate of one behavior should decrease the rate of the other behavior. Lester [12] has reviewed the theory and research on this issue. The present study, therefore, examined the impact of social vari- ables on both suicide and homicide rates.

This study then extends earlier research by cluster- ing the social variables using factor analysis, by exploring correlates of both current rates of personal violence and changes in these rates, and by contrast- ing suicide and homicide.

The choice of independent variables was based upon previous research.

(i) National levels of extraversion and anxiety were derived by Lynn [lo] based upon national

1249

1250 DAVID LESTER

indices. Anxiety was based on national levels of caloric intake, cirrhosis deaths, caffeine consump- tion. coronary deaths, and hospitalized psychiatric patients. Extraversion was based on cigarette con- sumption, divorce rates, accidental death rates, and crime rates, Lester [6] has studied the relationship of these two variables to rates of personal violence and reported that national anxiety scores were positively associated with suicide rates. while national extra- version scores were positively related to homicide rates.

(ii) Lester [ 131 used Henry and Short’s [2] theory to predict associations between the rated quality of life in regions and rates of personal violence. Henry and Short argued that suicide would be more common and homicide less common when there were fewer external constraints on behavior, for then people would tend to blame themselves more for their misery. Thus, if the quality of life is better, suicide should become more common and homicide less common. Lester confirmed this for the states of America.

(iii) In separate studies, Stack [14-171 has studied the relationship between suicide rates (but not homicide rates) and urbanization, gross national product per capita. the proportion of elderly, the birth rate, female participation in the labor force, the divorce rate, the percentage of religious books published, the percentage of Roman Catholics, government sanctions. population density, and female inequality in nations of the world.

The association between many of these vari- ables and rates of suicide and homicide can be predicted from Durkheim’s theory of suicide. Divorce and religious involvement both have ramifications for the social integration and regulation of the indi- vidual and thus may affect suicide rates. Lester [ 181 has studied the association of these two variables with the suicide rates of the states of America and reported a strong association. In Lester’s study of the American states. the percentage of the young and the elderly was also related to the suicide rate, a finding that makes sense since suicide rates rise with age. and so populations with more elderly should have higher suicide rates. A high birth rate leads to more and larger families which should strengthen family integration, thereby lowering suicide rates.

(iv) Homicide rates are higher in American states which are more urban (violent crime is much more common in urban areas) and in which fewer women participate in the labor force. This latter result is hard to predict theoretically but is a common empirical finding. It appears that, in America, female partici- pation in the labor force is associated with latitude, with more women participating in the labor force in the northern states where violent crime is less com- mon. It is of interest to explore whether this result is replicated in a cross-national study.

(v) The gross national product per capita, a measure of a nation’s productivity and wealth, has often been found to be associated with national suicide and homicide rates. The reason for this association may in part be related to the influences of the quality of life noted above. It may also be that

the wealthier nations more accurately classify and count suicidal deaths.

(vi) Nations differ in the extent of government sanctions against the people. According to Henry and Short’s theory mentioned above. the more govern- ment sanctions, the easier it will be to blame the government for personal misery. and so suicide rates should be lower and homicide rates higher.

(vii) Stewart and Winter [25] have explored the association between measures of female equality and rates of personal violence in nations of the world. and the present study explores these relationships in the present, more homogenous sample of nations.

METHOD

The sample was that used by Lynn [IO] of 18 industrialized nations: Australia. Austria. Belgium. Canada, Denmark. Finland. France, Ireland. Italy. Japan, the Netherlands. New Zealand, Norway, Sweden, Switzerland. the United Kingdom, the U.S.A. and West Germany.

The social variables are for 1970. Ratings of extraversion and anxiety for each nation come from Lynn [19], the quality of life from Estes [20], the gross national product per capita from the Census Bureau [21], the birth rate, the percentage of children and the percentage of elderly. the population density, the percentage of urban population. and female partici- pation in the labor force from the World Bank [22], the frequency of government sanctions and the per- centage of Roman Catholics from Taylor and Hud- son [23], the divorce rate from United Nations [24], the ratings of female equality from Stewart and Winter [25], the percentage of religious books pub- lished from Stack [ 171. and suicide and homicide rates from the World Health Organization [26]. The rates of personal violence are shown for the nations in Table 1.

RESC’LTS

The set of social variables was factor analyzed using the Statistical Package for the Social Sciences [27]. with a principal components extraction and a

Table I. Suude and homude ril,ea of [he “a,,~“?, per 100.000 per yur

Suude rate, Homicide TBICS

1970 IYXO I970 I980

Australia AliSIG Belgium Canada Denmark Finland FGiWX Ireland Italy J2ipafl Netherlands New Zealand Norway Sweden Swilzerland United Kingdom II S.A.

12-l II 0 I.5 I .9 24.1 2s 7 I5 IZ I6 5 21.5 I I I .6 II 3 140 2.0 ?.I ?I 5 31.6 0.7 I.3 71 3 25.7 2.0 33 15.4 I9 4 0.7 1.0

IX h.3 0.4 07 5x 7.3 0.X I .9

15.2 17.6 I.3 I .a x.1 IO.1 0.5 0.8 Y6 IO.8 I.? 1.3 x4 124 0.6 I.1

22 3 194 0.8 I.? I86 25 7 0.7 I .a X.0 xx 0.7 0.8

I I.5 II x X.2 10.5 WW Germany ?I 3 20.‘) I .4 I.?

Suicide and homicide

Table 2. Result of the factor-analysis of the social variables and rhe correlauons of

the factor scores with suicide and homicide rates

1251

I II III I\ \

Anxiely

ExtraversIon

Quality of hfe

GNP capita

Birth rate

46 Young

% Elderly

Population denslty

SO Urban population

Females in labor force

Government sanctions

% Roman Cathohc

Divorce rate

%Religious books

Female equahty:

Social

Economic

% Variance

Suude rates

I970

1980

Absolute Increase

% Increase

Male rate. 1970

Female rate. 1970

Hormcide rates

I970

I9RO

Absolute increase

% 1 ncrease

Male rate. 1970

Female rate. 1970

0.20 0.14 0.59*

0.82' 0.03 0.15

-0.71’ 0.47’ -0.30

0.86’ 0.19 -009

-0.10 -0.88’ -0.28

0.09 -0.84. -0.34

0.08 0.86’ -0.17

-0.20 0.19 0.05

0.17 -0.23 -0.26

0.25 0.32 0.84’

0.73’ 0.01 0.33

0.10 -0.06 -0.27

0.81* 0.10 0.25

0.02 -0.09 -0.29

0.24

0.19

27.3

-0.13 -0.13 -0.79’

-0.01 0.90’ 0.12

22.0 14.0 12.2

0.13

0.03

-0.20

-0.30

0.15

0.08

0.62* 0.51’ -007

0.60. 0.41’ -004

0.14 -0.09 0 07

-0.26 -0.39 - 0.09

0.60’ 0.519 -0.13

0.57; 0.4u* 0 06

0.88’

0.86’

0.61’

-0.18

0.87’

0.84’

-0.28 0.22 -0.12

-0.24 0.15 -0.15

-0.09 - 0.09 -0.19

0.1x -0.52’ -0.06

-0.26 0.2 I -0.13

-0.33 0.26 -0.1 I

0.56'

-0.39

-0.18

-0.17

-0.06

-0.22

0.14

0.78’

0.08 -0.12

0 24

0 62’

-0 36

-0.02

0.06

0.12

-0.04

-0.25

- 0.02

0.15

0.20

-0.23

-0.80.

-0 I3

0.2-l

0.58.

-0.26

0 88.

-0.08

-0.05

7.8

-0.13

- 0.08

0.09

0.55’

-0.01

-0.33

0.04

0.06

0.09

0.14

0.05

- 0.05

‘A high loadmp on the factor or a spificanl correlation (P < 0.05 or belter)

varimax rotation to produce orthogonal (indepen- dent) factors.

The factor analysis of the social variables resulted in five factors which are shown in Table 2. Factor I appears to tap wealth. Lynn’s extraversion and social disintegration with high loadings on extraversion, divorce rates and gross national product per capita. Factor II reflects the youthfulness of the nations with high loadings on the birth rate and the proportion of youth in the society. Factor III reflects female eco- nomic equality with high loadings on Lynn’s anxiety, female participation in the labor force and economic equality. Factor IV has high loadings on population density and female social inequality and is hard to label. Factor V is loaded on low urbanization and religiosity and seems to reflect traditionalism in the society.

The correlations of these factors with suicide and homicide rates in 1970 and in 1980 and with changes in these rates from 1970 to 1980 are also shown in Table 2. It can be seen that suicide rates were correlated with both Factors II and III. Suicide rates are higher in societies with a more elderly population and with greater female economic equality.

In contrast, homicide rates were correlated only with Factor I. Homicide rates were higher in societies with a high divorce rate. more government sanctions, and a high gross national product per capita.

It can be seen in Table 2 that the predictors of male and female rates of suicide and homicide were identical.

Interestingly, the same factors predicted suicide and homicide rates in 1980. probably a reflection of the fact that suicide and homicide rates are quite

stable over time. Suicide rates in 1970 and 1980 were strongly associated (Pearson r = 0.91) as were homi- cide rates (r = 0.98).

The social variables in 1970 that predicted the changes in suicide rates by 1980 were different de- pending upon whether the absolute increase or the percentage increase was used as the dependent vari- able. For suicide rates, no social variables used in the present study predicted the absolute increase in the suicide rate from 1970 to 1980. However, Factor V (a measure of traditionalism) was associated with a greater percentage increase in the suicide rate.

In contrast, Factor I (wealth and social disintegra- tion) predicted the absolute increase in homicide rates, while Factor III (female economic equality) predicted the percentage increase. Homicide rates increased more in the wealthier societies and propor- tionately more in societies with less female economic equality.

DISCUSSION

This study has illustrated the usefulness of studying a large set of social variables rather than focusing on merely one or two when searching for correlates of national suicide and homicide rates. For example. a study of single variables might identify divorce rates as a correlate of national suicide rates. The present study showed, however, that divorce rates are strongly associated with government sanctions, the gross national product per capita, scores for the national character trait of extraversion. and (nega- tively) with the quality of life. These variables as a cluster correlated in the present study with homicide

1252 DAVID LESTER

rates, and it can be seen that to isolate one of these five variables as the critical variable would be mis- leading.

The second important finding of this study is that the correlates of national homicide rates were different from those for suicide, but not the opposite. Lester’s [12] conclusion that theory and research evidence supports the proposition that suicide and homicide are contrasting behaviors with opposed correlations with social variables was not borne out by the present study.

Thirdly, the same social variables that were associ- ated with suicide and homicide rates in 1970 also predicted 1980 suicide and homicide rates, primarily because national suicide and homicide rates are stable over time. Important difference were found, however, in the social variables that predicted changes in national suicide and homicide rates. Predictors of changes in the rates were quite different from corre- lates of the rates, and these predictors differed for predicting absolute changes in the rates and and for predicting percentage changes in the rates.

In particular, during the 1970s suicide rates increased more (proportionately) in the traditional societies, whereas homicide rates increased more (proportionately) in societies where female economic equality was lagging behind.

Thus, correlates of current rates of personal vio- lence differed quite considerably from correlates of changes in these rates.

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