Wednesday, November 9, 2022

Estimates suggest high-speed wireless internet significantly increased teen girls' mental health diagnoses--by 90%--relative to teen boys over the period when visual social media became dominant among teenagers

Social Media and Teenage Mental Health: Quasi-Experimental Evidence. Nov 2022. Elaine Guo. Working Paper.

Abstract: Teenage mental health has been a source of growing concern over the past decade, with recent whistleblower testimony pointing to the mental health risks of spending time on social media platforms, especially for girls. This paper investigates the extent to which social media are harmful for teenagers, leveraging rich administrative data from the Canadian province of British Columbia and quasi-experimental variation related to the rollout of wireless internet there. I show neighbourhoods covered by high-speed wireless internet have significantly higher social media use, based on Google search volumes. In the main analysis, I link federally-collected broadband data with 20 years of student records that provide detailed information about individual student health. I then estimate a triple-difference model using this novel data linkage, comparing teen girls to teen boys in terms of school-reported mental health diagnoses, before and after major social media launches, and across neighbourhoods with and without access to high-speed wireless internet. Estimates suggest high-speed wireless internet significantly increased teen girls' mental health diagnoses -- by 90\% -- relative to teen boys over the period when visual social media became dominant among teenagers. I find similar effects across all subgroups, indicating they are not driven by differences in confounding characteristics.  When applying the same strategy, I find null effects for placebo health conditions -- ones for which there is no clear channel for social media to operate. The evidence points to adverse effects of visual social media, in light of large gender gaps in visual social media use and documented risks. In turn, the analysis calls attention to policy interventions that could mitigate the harm to young people due to their online activities.

Despite Google's filtering/ranking, users still appear to be able to tailor their information exposure to maintain their prior beliefs, hence defying that algorithmic impact

Adapting the Selective Exposure Perspective to Algorithmically Governed Platforms: The Case of Google Search. Laura Slechten et al. Communication Research, April 30, 2021, Volume 49, Issue 8.

Abstract: Experimental research on selective exposure on online platforms is generally limited by a narrow focus on specific parts of the information selection process, rather than integrating the entire sequence of user-platform interactions. The current study, focusing on online search, incorporates the entire process that stretches from formulating an initial query to finally satisfying an information need. As such, it comprehensively covers how both users and platforms exercise agency by enabling and constraining each other in progressively narrowing down the available information. During a tailored online experiment, participants are asked to search for social and political information in a fully tracked, manipulated Google Search environment. Although the results show a structural impact of varying search result rankings, users still appear to be able to tailor their information exposure to maintain their prior beliefs, hence defying that algorithmic impact. This corroborates the need to conceptually and methodologically expand online selective exposure research.

Portfolio outcomes: Higher IQ is not associated with enhanced investment performance

The effects of personality and IQ on portfolio outcomes. Chris Firth et al. Finance Research Letters, November 4 2022, 103464.


• We investigate the effects of personality (Big Five traits) and IQ on individuals’ stock portfolio outcomes (activity, biases and performance)

• We use 1238 customers’ responses to a self-report survey and matched with their portfolio trading data.

• Traits have small but significant effects; higher IQ is not associated with enhanced investment performance.

• Other factors, such as customer age, portfolio size and portfolio risk, much better explain outcomes. Financial literacy shows little effect.

Abstract: We use responses to a self-report survey and matched administrative data to investigate the effects of personality (Big Five traits) and IQ on individuals’ stock trading portfolios. Traits have small but significant effects: openness and extraversion are associated with undesirable outcomes whereas conscientiousness is associated beneficially. Higher IQ is associated with lower trading activity but not enhanced investment performance. We postulate these factors influence outcomes in a complex manner, and exert over long timeframes. With portfolio size held constant, financial literacy has little effect. Other factors, such as customer age, portfolio size and portfolio risk, better explain outcomes.

JEL: D14 D91 G11

Keywords: individual decision-makingpersonality traitsBig Fiveinvestment biasesfinancial literacyIQ

3.1. Big Five personality traits

Internal consistency, measured by Cronbach's alpha, ranges from 0.31 to 0.72 for the five TIPI-derived traits and is consistent with (Gosling et al. 2003) (who also show strong correlations from a much longer inventory).

Coefficient sizes from the regressions for trait variables are consistently small7. Typical is the coefficient of 0.05 on conscientiousness (Big5_C) for the regression on Sharpe (investment performance). We interpret this as saying that on average a one standard deviation increase in conscientiousness improves performance by 5% of a standard deviation of the variable Sharpe. Despite the weak effects, the presence or not of statistical significance and the signs of coefficients offer useful insights. In summary: openness (Big5_O) has a negative association with login rate and positive associations with overconfidence and idiosyncratic risk; extraversion (Big5_E) has positive associations with overconfidence and negative associations with idiosyncratic risk and investment performance. We could explain this by suggesting that extraverts – being easily bored – take excessive, unrewarded risk. We might also speculate they would trade more and be more vulnerable to the disposition effect but that does not feature in our results.

Conscientiousness (Big5_C) has positive associations with overconfidence and investment performance. Roberts et al. (2011) report that conscientious people earn more money, which is comparable to our finding of a positive link between conscientious individuals and better returns. Kleine et al. (2016) report that openness tends to have a negative impact on portfolios; we too see that openness is associated with less desirable portfolio outcomes.

3.2. IQ

The IQ scores in our sample are as expected for a general population (see online appendix); we may reasonably state that the brokerage customers are not exceptionally intelligent. The regressions indicate that IQ very weakly predicts lower portfolio activity8. We observe no significant associations between IQ and biases of disposition effect and idiosyncratic risk, though there is a lessening effect for overconfidence. We report no statistically significant effect of IQ on the economically relevant measure (Sharpe). Although these coefficients are directionally consistent with results in (Grinblatt et al. 2012), their lack of statistical significance is somewhat surprising. However, there could be plausible reasons this. Firstly, we have a much smaller sample size than do Grinblatt et al. (2012), and, secondly, the IQ measure we use – from Raven and Court (1998) – is arguably independent of formal education (Almlund et al. 2011) which avoids potentially confounding IQ with numeracy9. Numeracy is known to be an important predictor of success in everyday risk and financial decisions (Smith et al. 2010Cokely et al. 2012Peters 2012).

3.3. Financial literacy

Financial literacy (FinLit) shows no statistically significant effects across six of the regressions, the main exception being the (undesirable) positive coefficient on overconfidence (OverCon). There is also weak evidence of a reduction in the disposition effect (Disp). Fernandes et al. (2014) find that effects of financial literacy diminish when variables for psychological traits are added. Instead, we observe an analogous role for portfolio size (Size). In regressions with Size excluded, financial literacy shows significant effects (see online appendix). These coefficients moderate sharply with Size included (expressed alternatively: with portfolio size held constant, financial literacy does not affect outcomes). For example, excluding Size, a one standard deviation increase in financial literacy lowers idiosyncratic risk by 8% of a standard deviation of the variable Idio. With Size, the effect of literacy is not distinguishable from zero and the coefficient for Size is 17% (see Table 4). We record a correlation of 0.21 (significant at 1%) between IQ and financial literacy (see online appendix). Muñoz-Murillo et al. (2020) likewise find that individuals with higher cognitive abilities are more financially literate.

Taken together, these results hint at a nuanced causal relationship in which those with larger portfolios are more financially literate—either because those more literate are confident enough to hold larger portfolios or because those who plan to hold larger portfolios deliberately acquire a higher level of literacy—but that variance in financial literacy over and above that due to portfolio size has no further effect.

We repeat our earlier caution that the high but uniform financial literacy of our sample customers – in itself noteworthy – could hinder inferences. Moreover, financial literacy could be endogenous, leading to biased parameter estimates. We attempt to overcome this by conducting age-instrumented estimates of the effects of financial literacy (see online appendix) based on the premise that customer age is exogenous, together with evidence from Agarwal et al. (2009) that financial mistakes decrease with age (until the onset of mental impairment). While our IV results are consistent with the overall pattern in our main analysis, we conclude that the methodological hurdles surrounding our financial literacy variable leave the question of its effects unsettled.

Government, trusts, and the making of better roads in early nineteenth century England and Wales

Government, trusts, and the making of better roads in early nineteenth century England and Wales. Alan Rosevear, Dan Bogart & Leigh Shaw-Taylor. Univ. of California at Irvine, Aug 31 2022.

Abstract: This paper introduces new data to explain how public, private, and non-profit sectors sponsored, financed, and technically developed better roads in early 19th century England and Wales. Our findings show that central Government direct financing was limited to sections of the politically important London-Holyhead Mail Road. By comparison non-profit organizations, known as turnpike trusts, built more new roads by attracting private investors and capable surveyors. We also show the Government Mail Road had the highest quality. Nevertheless, most turnpike trust roads were good quality, indicating their practical achievements. The  broader implications for infrastructure and state capacity are also explained. 

Keywords: State capacity, infrastructure, roads, turnpike trusts, non-profit sector, public private partnerships

JEL: N7, N4, H1, R4

Adolescent females: Rape victimization was predicted by greater curvaceousness and weight but was unrelated to interviewer-rated attractiveness

Association between Dimensions of Physical Attractiveness and Risk of Rape Victimization among Adolescent Females. Anthony W. Hoskin &Daniel Moody. Journal of Aggression, Maltreatment & Trauma, Nov 6 2022.

Abstract: This study addresses the following question: “Does female physical attractiveness predict the risk of rape victimization?” Data were analyzed from a large sample of females who participated in the National Longitudinal Study of Adolescent to Adult Health (Add Health). Three conceptualizations of physical attractiveness were operationalized: overall attractiveness, curvaceousness, and weight. Bivariate analysis revealed that rape victimization was predicted by greater curvaceousness and weight but was unrelated to interviewer-rated attractiveness. Respondent age, Hispanic ethnicity, race, general health, physical maturation, and number of sexual partners were added to multivariate models in a stepwise fashion, but physical attractiveness and rape victimization were found to be unrelated in all models, and the positive association between weight and victimization fell to statistical non-significance when general health was added to the model. By contrast, curvaceousness consistently predicted greater victimization risk across all models. Among control variables, females who are older, less healthy, and who have more sexual partners face a higher risk of victimization. Add Health data do not present a straightforward picture of the relationship between various dimensions of physical attractiveness and rape victimization. Findings, study limitations, and theoretical implications are discussed.

Keywords: Sexual assaultrapevictimizationphysical attractiveness

Individualization and the decline of homicide: England 1250–1750

Individualization and the decline of homicide: England 1250–1750. Mark Cooney, Jeffery Patterson. Journal of Criminal Justice, November 3 2022, 101997.

Abstract: A key issue in criminology is to account for variation in rates of violence across time and place. An important variable largely neglected in the literature is individualism. Building on theoretical ideas proposed by Durkheim, Black, and Baumgartner, we illustrate the role of increased individualism with a case study: the decline of homicide in England, 1250–1750. The qualitative historical materials we present reveal the growth of more individualized conflicts evident in less third-party partisan intervention and a reduced concern with honor. More individualized conflicts were, in turn, a product of a more individualized society, one characterized by increased social distance and mobility. As conflicts individualized they became less lethal, resulting in declining aggregate rates of homicide. Although the case study is historical, our argument has implications for understanding contemporary criminal violence.