sou · GTB381d6 · 2006-01-01 00:00:00 — In both domains, the mean value was lower in 1996 than in 1970, signifying a better adjustment in 1996. Also in a third relational domain, relations to teachers, the mean value was lower in 1996 than in 1970, although this difference only tended towards significance (p < .01). In a fourth domain, relations to mother, there was a tendency towards a higher mean value in 1996 than in 1970, which suggested a some- what poorer adjustment in 1996 (p < .01). The effect sizes of all differences were small, however (-.31 to .17). Variability in overall adjustment. The size of the standard devia- tion in each domain was also compared between 1970 and 1996. Significant differences were found in two domains: Self-esteem and antisocial behavior (Table 1). In both domains, the standard devia- tion was larger in 1996 than in 1970. While the standard deviations in self-esteem and antisocial problems were significantly larger in 1996, there were no significant differences in the mean values of the distributions, which might indicate a polarization over time. This was tested in the following way: Two somewhat arbitrary cut-off points were set in each of the two overall sum-score distributions: one cut-off point for high scores (poor adjustment) at one standard devia- tion above the mean; and one cut-off point for low scores (good adjustment) at one standard deviation below the mean (pooled standard deviations). With these cut-off points, of the girls had high scores and of the girls had low scores in the self- esteem distribution in 1970; the corresponding percentages in the same distribution in 1996 were 19.4 and 18.0, respectively, which means that the percentages were larger at both ends of the distri- bution in 1996 than in 1970. The increase in percentages was only significant at the negative end (z = 3.45, p < .01, one-tailed), how- ever, and not at the positive end (z = 1.12, ns), which does not give full support for the polarization hypothesis in the self-esteem domain. In the antisocial behavior domain, of the girls had high scores and had low scores in 1970; the corresponding percentages in 1996 were 15.5 and 15.7, respectively, which means that the percentages were larger at both ends of the distribution in 1996 than in 1970. Both increases were significant (z = 2.01, p < .05, and z = 3.24, p < .01, respectively, one-tailed), which supports the hypothesis of a polarization process in the antisocial behavior domain. Number of Adjustment Problems Within Domains Next, mean numbers of problem scores in the nine domains were compared between 1970 and 1996. The results are presented in Table 2. No significant differences in mean numbers of adjustment problems were found. The mean number of problems in self- esteem was somewhat higher in 1996 than in 1970, however, and this difference had a tendency towards significance (p < .01). Number of Well-Adjusted Items Scores Within Domains Finally, mean numbers of item scores signifying good adjustment in the nine domains were also compared between 1970 and 1996 (Table 2). A significant difference in mean number of well-adjusted item scores was found for relations to peers, where the mean number of well-adjusted item scores was higher in 1996 than in 1970 (p < .05, corrected for mass significance). In addition, the higher mean number of well-adjusted item scores in relations to parents tended towards significance (p < .01). Also for these differences, the effect sizes were small, however (.32 and .19, respectively). As already described in the Method section, the immigration to increased substantially between 1970 and 1996. To investi- gate the extent to which the results were influenced by this increase in the ethnical heterogeneity of the population, all of the previous comparisons between the two cohorts were run a second time, excluding from the 1996 cohort all girls with a mother and/or a father born in a non-Nordic country. Overall adjustment within domains. The significant differences in mean values of overall adjustment in relations to parents and rela- tions to peers, which were found in the comparison between the 1970 cohort and the complete 1996 cohort, were also found in the comparison with the reduced 1996 cohort (relations to parents in the reduced 1996 cohort: m = 17.7, p < .05, corrected for mass significance; relations to peers: m = 27.2, p < .05, corrected for mass significance). In addition, the difference in the mean value for relations to teachers, which only tended towards significance in the comparison with the complete 1996 cohort, also reached signifi- cance in the comparison with the reduced 1996 cohort (m = 14.4, p < .05, corrected for mass significance). Concerning differences in standard deviations, a significant difference in the standard deviation of self-esteem was found in the comparison with the reduced 1996 cohort (sd = 7.6, p < .05, corrected for mass significance), while the difference in the stan- dard deviation of antisocial behavior only had a tendency towards significance (sd = 6.8, p < .01). The polarization process in anti- social problems could no longer be demonstrated when the 1970 cohort was compared to the reduced 1996 cohort: The increase in the percentage of girls with a good adjustment remained significant (, z = 3.16, p < .01, one-tailed), but the increase in the percentage of girls with negative adjustment did not (, z = 1.15, ns, one-tailed). In the self-esteem domain, the results were similar to the results of the comparison with the complete 1996 cohort: the increase in percentage of girls with poor adjustment was significant (, z = 3.16, p < .01, one-tailed), while the increase in the percentage with good adjustment was not (, z = 1.26, ns, one-tailed). Number of adjustment problems within domains. As in the com- parison between the 1970 cohort and the complete 1996 cohort, no significant differences in mean numbers of adjustment problems were found in the comparison with the reduced 1996 cohort. A tendency towards a decreased number of problems in relations to peers was found in the reduced cohort (m = 0.6, p < .01). The tendency towards an increased number of problems in self-esteem, which appeared in the comparison with the complete 1996 cohort, was not found in the reduced cohort, however (m = 1.9, ns). Number of well-adjusted item scores within domains. Also for the occurrence of good adjustment, the results were similar in the comparisons including and not including girls with immigrated parents: The mean numbers of well-adjusted item scores in rela- tions to parents and peers were significantly higher in the reduced 1996 cohort than in the 1970 cohort (relations to parents: m = 6.3, p < .05, corrected for mass significance; relations to peers: m = 11.9, p < .05, corrected for mass significance). This study is a comparison over a quarter of a century of self- reported adjustment in a cohort of 15-year-old girls in a Swedish community in 1970 and a cohort of 15-year-old girls in the same community in 1996. The study covered several adjustment domains: physical problems, emotional problems, self-esteem, anti- social problems, relations to parents, relations to teachers, relations to peers and sexuality. Within each of these domains, the two school-cohorts were compared with regard to the occurrence of adjustment problems and of positive adjustment. Overall adjust- ment and especially the variability in overall adjustment were also considered. The main conclusion from these comparisons was that, at large, girls adjustment in mid-adolescence appeared to be remarkably similar over the 26-year period. In most domains, adjustment problems were equally common in 1996 as in 1970, with two exceptions: Problems with self-esteem and antisocial problems appeared to be more common in 1996. In the antisocial domain, evidence was found of the polarization process suggested by (1996): not only were there somewhat more girls in 1996 than in 1970 who had a poor adjustment (15 versus ), but there were also more girls with a good adjustment (16 versus ). Positive adjustment also appeared to be more common in girls relations to important others, especially peers; the effect sizes for the differences were small, however. Translating these findings into time trends, they suggest a substantial stability in the adjustment of Swedish mid-adolescent girls. One should remember, however, that only two time points were compared. Although few differences were detected between the 1970 and 1996 cohorts, time trends might have shifted during the intervening period. For example, when Achenbach and colleagues (Achenbach et al., 2003) compared adjustment problems reported by the parents of American children and adolescents over a time period almost as long as in the present study (23 years), they had measurements from three time points: 1976, 1989 and 1999. They found that adjustment problem scores increased and compe- tence scores decreased over the first time period, but that these trends were reversed in the second time period. In this way, the deterioration in the adjustment of American children and adoles- cents was less apparent after 23 years than after the first 13 years of the period. As already described, the evidence in favour of a polarization process in young peoples adjustment over past decades (, 1996) was limited to antisocial problems and was not found in any of the other adjustment domains. The finding is important, how- ever, in pointing to the possibility of changes over time that are not captured by the study of mean values; as might be noted, the mean values of the separate distributions for good and poor adjustment in the antisocial domain were unaffected by the polarization process. A large number of statistical tests were made in the present study, and it was necessary to guard against the mass significance problem by applying very strict nominal significance levels. This, of course, diminished the power of the tests we carried out, and it raises the question whether we have failed to detect important time differences because of this. According to the following reasoning this is not likely, however: In the comparisons of the sum scores in each domain there were approximately 500 girls in each group and the nominal significance level was .05/36. With these conditions, the effect size necessary to obtain a significant result with a power of is .28x. To carry out this computation, the program Simple Interactive Statistical Analysis (SISA), available on the internet, was used (interpolation was undertaken to find the exact power level). This effect size is normally regarded as small, which means that any time difference in the studied scales that was of a medium or large effect size would almost certainly have been detected in the present study. In their Academia Europaea study, Rutter and (1995) reported evidence of a marked increase in depression in recent birth cohorts. Although this evidence mainly concerned depressive disorders, we still expected to find some traces of this time trend in our comparison of girls reports of emotional problems in 1970 and 1996. No indication of such an increase was found, however, neither in the occurrence of negative adjustment, nor in the vari- ability in overall adjustment in the emotional domain. A visual inspection of single problems related to depression also suggested that these problems were equally common in both cohorts (see Appendix): In 1970, 14 percent of the girls reported feeling sad and depressed, while the corresponding figure in 1996 was 12 percent. Similar findings were made for feeling like not wanting to live anymore (11 vs. ) and seldom feeling that it was wonderful to be alive (in both cohorts). Physical problems that might be related to depression, such as bad appetite and sleeping distur- bances, were also equally common in 1970 and 1996. These find- ings are in line with the results for Dutch children and adolescents reported by Verhulst et al. (1997): They found somewhat higher scores for Dutch children in 1993 than in 1983 on the item unhappy, sad, depressed but did not find any changes on the anxious/depressed syndrome scale. Achenbach et al. (2003) did find higher scores for American children and adolescents on the anxious/depressed scale in 1989 than in 1976, but these scores were lower in 1999 than in 1989. In all, these findings are not supportive of an ongoing increase in depressive feelings and symptoms among young people. In contrast to the lack of evidence of an increase in emotional problems, some findings in the present study indicated an increase in problems related to self-esteem: There was a tendency towards a higher mean number of adjustment problems in the self-esteem domain in 1996 compared to 1970 (p < .01), and the proportion of girls who had an overall sum score above one standard deviation from the mean increased from 11 to (p < .01). The explora- tion of changes in frequencies of single adjustment problems indi- cated that the increased problems of self-esteem might have been related to appearance and attractiveness (see Appendix): The percentages of girls reporting that they seldom were satisfied with their looks increased substantially (from 22 to ). In addition, more girls often felt ashamed of themselves (increasing from 5 to ), would have liked to change themselves fairly or very much (from 17 to ), and often blamed themselves for things they knew they really could not help (from 7 to ). The substantially increased percentage of girls who felt very or not at all popu- lar among boys might be added to this picture (from 35 to ; see the sexuality domain in Appendix). This suggests that the increase in self-esteem problems might have been related to an increased impact of societal ideals of attractiveness. Internalization of societal standards of attractiveness – usually labelled thin-ideal internalization – has been suggested as a risk factor for the development of body-image disturbances and eating disorders (, 2001). Unfortunately, it is not known from the present study whether girls reduced satisfac- tion with their appearance was related to increases in the occur- rence of eating disturbances. Comparative data on eating distur- bances are missing from the data sets used in this study. In itself this is a clear illustration of the absence of interest in this issue in the early 70s when the symptom questionnaire used in this study was constructed. Relations to Parents and Peers Signs of an improved adjustment were found in the girls relations to important others, especially in relations to peers, but also in relations to parents (although it might be noted that there was a weak tendency in the opposite direction for girls relations to their mothers when overall adjustment in this domain was studied). These findings of improvements in relations to parents and peers occurred over a period that has been characterized by substantial transformations in family patterns and family functioning in . In the 1970 school cohort, of the girls were still living with both their parents at age 15. In 1996 this figure had dropped to . Moreover, most mothers with small children were not employed outside the home in the 50s when the 1970 cohort was in their pre-school years. In the eighties, when the 1996 cohort was in their pre-school years, most children were in some kind of day care. Although it is difficult to speculate about causal connec- tions, it might be hypothesized that the more positive perceptions the girls had of their peer relations in 1996 were related to their early social training in safe and familiar day care environments. Another change in the Swedish society during the time period, which might have had some influence on the picture of young girls adjustment, is the increase in immigration. When girls with immi- grated parents in the 1996 cohort were excluded from the compari- son, the polarization in the antisocial problem domain could no longer be demonstrated: The significant increase in the proportion of girls who had a good adjustment in this domain remained, but the increase in the proportion of girls who reported a poor adjust- ment no longer reached significance. This suggests that the increased ethnical heterogeneity in the population might have contributed to the increased variability in the antisocial problem domain.1 Beside this difference, no large discrepancies were found between the time comparisons including and not including girls with immigrated parents. Limitations of the Study One limitation of the study has already been considered: Only two time points were involved, and we do not know what has happened during the intervening period. Three additional points should be made concerning possible limitations: First it should be noted that the samples investigated in the present study were school-cohorts of 15-year-old girls from only one Swedish community. The repre- sentativeness of those who participated in the basic data collection in the program was investigated by (1973), who found the cohort to be reasonably representative of many Swedish urban populations with regard to parents education and intelli- gence of the children. Secondly, as described in the Method section, girls with severe adjustment problems were over-represented in the drop-out from the 1970 cohort (, 1972, 1986). No similar analysis could be performed of the drop-out in 1996. There are no reasons to assume, however, that the bias in the drop-out would be very different between the two cohorts, especially since the drop-out is of a similar size at both time points. If this assumption is correct, the bias in the drop-out should not have had a significant influence on the relative differences in frequencies of adjustment problems in the two cohorts, although it of course might have influenced the absolute frequencies themselves. Finally, we do not know to what extent respondents interpret the questions in a similar way when surveys are repeated after a long time interval. In this study, the issue probably is of most concern when interpreting the results on peer problems: The Swedish word kamrat that is used for peer in the peer ques- tions might be somewhat less natural for teenagers to use today than in 1970. It cannot be decided from available data whether the girls have thought of comparable groups of friends and peers when answering the questions in 1996 and 1970. If the girls in 1996 have thought of a more limited circle of close friends, this might be an alternative explanation of their lower problem rates than the influ- ence of time trends. In the present study we have investigated time trends in measures of good and poor adjustment in different adjustment domains. Time trends might also appear in the multivariate distributions of different adjustment problems considered simultaneously, inde- pendently of any changes in their frequencies. Future studies should therefore also consider the tendencies for various adjust- ment problems to form syndromes together at the level of the indi- vidual, which is possible within a person-oriented frame of refer- ence (, 1997; et al., 2003). This approach may for example cast a new light on the hypotheses presented by (1996), if the processes described by him operate multi-dimensionally. It is only with a person-oriented approach that account can be taken of whole patterns of adjust- ment (, 1997; , , & El- Khouri, 2003). Another issue is whether externalizing and internalizing adjust- ment problems are related to the same interpersonal relations and to the same social conditions today as in the 70s. For example, could it be the case that the associations between adjustment problems and family structure have changed as a result of the large increase in family break-ups over the past decades? 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