Mental Ability and its Relation to Physical Health and Social Economic Status
- Author:
Maller
Institute of School Experimentation, Teachers College, Columbia University The purpose of this investigation was to study the relationship between mental ability and certain physical defects among the pupils of the various elementary public schools of New York City, and the relationship between these factors and the social economic status of the neighborhoods where the respective schools are located. Sources of Data. During the year 1932, all the fifth grade pupils of the New York public schools were examined with a battery of intelligence tests, including the National Intelligence Test and the Pintner Survey Test. This educationally homogeneous group, tested under the auspices of the Board of Education, included some 100,098 pupils enrolled in 579 schools. The records of achievement and progress were also obtained for each of the public schools. During the same year the pupils of Grade I of all schools were given health examinations under the auspices of the Department of Health. These included examinations of eyes, ears, teeth, nose, throat, heart, nutrition, etc.
The Distribution of Intelligence. In view of the fact that these 100,098 fifth grade pupils represent a cross section of the total population of the city, the distribution of their scores (I.Q.’s) is of considerable interest. It is particularly interesting to compare it with other distributions. Figure 1 presents a comparison between our distribution and the distribution of I.Q.’s presented by Terman. The latter is based on the scores of 905 unselected children from schools in California.1 Both distributions are in terms of percentages. It will be seen from Figure 1 that the two distributions differ considerably. Terman’s distribution is leptocurtic, peaked in the center, while our distribution is platocurtic, relatively flat at the center. In the former there are about twice as many pupils with i L. M. Terman, The measurement of intelligence, New York, Houghton Mifflin, 1916, chap. V. 101
I.Q.’s between 90 and 110 while in the latter there is a correspondingly greater proportion of eases at the extremes. The differences are due to the difference in the nature of the test and the population tested. Variability of Intelligence. How do the schools of the city vary with regard to the average intelligence of their pupils? The distribution of the averages of the respective schools and neighborhoods were computed for each measure. Figure 2 shows the distribution of intelligence scores (I.Q.’s) of 100,098 fifth grade pupils. It also shows the distribution of the averages of the 579 schools and the averages of some 300 health areas, into which the city is divided.
Fig. 1. The distribution of intelligence: comparison between New York and California data It will be seen from Figure 2 that the distribution of scores ranged from 50 to 160 with a mean of 100.2 and an S.D. of 20.9 and that the respective public schools vary enormously with regard to average intelligence. The means ranged from 70 to 122 with an average of 100.0 and an S.D. of 9.4. The means of neighborhoods ranged from 79 to 120 with a mean of 100.5 and an S.D. of 8.2. This inter-school heterogeneity or intra-school homogeneity (with regard to intelligence) may be expressed in terms of the ratio between the sigma of the means to the sigma of the total population. In our case this correlation ratio is .45 ? .02. For the neighborhoods this correlation ratio is .40 ? .03. It seems then that the respective schools as well as the respective neighborhoods are in no sense random samples of the total school population.2 2 See J. B. Mailer, Economic and social correlatives of school progress in New York City, Teach. Coll. Bee., 1933, 34, 655-670. Individuals, N-100,098. Schools, N-579. Neighborhoods, N-300. Fig. 2. The distribution of intelligence: individuals, schools, and neighborhoods
Health Measures. A summary of the results of health examinations is shown in Table 1. This is based on the examination of 140,230 pupils of Grade I and Kindergarten of all New York City schools (including both public and parochial schools). Table 1 presents the incidence of defects per 1000 cases. It reads as follows: Of each 1000 children examined in Manhattan, 239 were found free from all defects, 91 were found to have visual defect, 496 had carious teeth, etc. Table 1 Incidence op Physical Defects among Pupils op Grade I, New York City Schools (per 1000 children inspected) Location Free from all Defects Visual Defects Carious Teeth Mouth Hygiene Nasal Obstruction Tonsils Heart Defect Orthopedic Nervous Disturb. Malnutrition Manhattan Bronx Brooklyn Queens Richmond Total, city Average of neighborhoods S.D. of neighborhoods 239 367 348 374 457 335 330 87 91 83 85 31 48 74 77 51 496 338 434 418 357 425 426 93 52 7 41 13 33 32 35 43 324 237 157 130 28 200 209 97 373 277 256 261 168 283 291 79 20 35 19 23 10 22 23 18 27 7 10 1 13 14 9 5 12 5 5 1 6 6 4 294 211 183 126 41 199 201 81
Variation of Health Measures. Striking variation was found among the schools with regard to the various measures of health. Thus, for the city as a whole, 34 per cent of the pupils were found to be free from all defects, but the indices of the schools ranged from 8 per cent to 71 per cent free from all defects. Similarly, the incidence of visual defects for the school population is 7 per cent, but in the schools it ranged from 1 per cent to 22 per cent. In malnutrition the incidence was 20 per cent for the total of the school population, while in the schools it ranged from 4 per cent to 72 per cent.
The eta, expressing the relationship between the composite measure of health and location, was .29 ? .03. It was shown above that for intelligence the correlation ratio was .45 ? .02. Apparently the pupils of a given school in New York City are slightly more homogeneous with regard to intelligence than with regard to aspects of health, and, conversely, there is greater variability among schools in respect to intelligence than in respect to health. Correlation. The records of health were available by schools, for each of the 579 elementary schools. The correlation between average intelligence score and the percentage of pupils having no physical defect was .5085 ? 0.2. For the respective measures of health the correlations were as follows:
I.Q. and visual defect ?.3991 ? .02 I.Q. and teeth defect ?.4977 ? .02 I.Q. and tonsils ?.2643 ? .03 I.Q. and malnutrition ?.2792 ? .03
The average correlation between I.Q. and these incidences of defect was ?.3601. The average inter-correlation among the measures of health was .5106. Apparently measures of different aspects of physical health correlate slightly higher with one another than they correlate with mental ability. The relationship among measures of health is also evidenced in the large number of cases having more than one defect. Thus, while fully 34 per cent of the children were free from all defects, among the remaining 66 per cent the incidence was a little more than 2.0 defects per child.
Data Concerning Neighborhoods. It is obvious that the correlation between average intelligence and index of health is partly due to the marked differences in the nature of the population residing in the various neighborhoods where the respective schools are located. As was stated above, New York City is divided into some 300 health areas or neighborhoods with about 2 elementary schools per neighborhood. Federal and municipal statistics are computed by these neighborhoods.3 Various data were available for each neighborhood, including the above measures of health, vital indices (birth rate and death rate), rate of juvenile delinquency, and economic status based on values of homes and rentals. The average I.Q. of all fifth grade pupils residing in each neighborhood was computed (Fig. 1). These averages were then correlated with the above neighborhood factors. The correlations between average intelligence and some of these factors will be presented : Death rate ?.4266 =fc .03 Infant mortality rate ?.5125 ? .03 Juvenile delinquency rate ?.5681 ?.03 Birth rate ?.3409 ? .04 Economic status (Federal census figures of value of home rentals) +.5006 ? .03
Health and intelligence, economic status constant +-28 ? .04 s A more detailed presentation of these neighborhood factors is presented by the writer in Vital indices and their relation to psychological and social factors, Human Biol., 1933, 5, 94-121.
The correlations indicate that mental ability is correlated positively with desirable characteristics such as health and economic status. It correlates negatively with all undesirable characteristics as high mortality and delinquency.
Factor Analysis. The present considerations dealt primarily with the correlation between mental ability and other factors. The limited space will not permit the presentation of the various intercorrelations among the 14 other variables (measures of health, social economic status and vital indices). Only one aspect of the intercorrelations will be presented. The tetrad difference analysis was applied to the table of 105 intercorrelations. There were a number of large and significant tetrad differences, indicating the presence of group factors.
After the elimination of those correlations which were definitely curvelinear (e.g., birth rate) the remaining ones were combined or “pooled” into four composites. (1) Intellect, including scores oil tests of intelligence, achievement and rate of school progress. (2) Health, including the inverted rates of physical defects, disease, and mortality. (3) Character, or social adjustment, including the inverted rate of juvenile court arraignment, delinquency, and truancy. (4) Economic status, including occupational level, home value and rental. The resulting tetrad differences were rather small, the largest one being less than three times its probable error (average correlation, .38; largest tetrad difference, .05; probable error, .02). This indicates that the four groups of measures may be considered as having one factor common to them. This common factor may be looked upon as the developmental status of the group or neighborhood which expresses itself in the level of physical, intellectual and social adjustment.
Summary
The populations of different schools of New York City were found to vary enormously in regard to measures of mental ability and physical health. Similar variability was found among the neighborhoods of the city with regard to vital indices and social economic measures. The respective schools or neighborhoods are in no sense random samples of the total city. The implication for studies frequently conducted in one school or neighborhood is obvious.
Mental ability was found to correlate positively with measures of health and with index of social economic status. Even when social economic status is held constant, the correlation between intelligence and health remains significantly positive. Mental ability was found to correlate negatively with death rate, infant mortality, juvenile delinquency, and birth rate.
An analysis of intercorrelations revealed the possible presence of a factor common to measures of intellect, physical vitality, and vocational and social adjustment.
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