The relationship between income and health using longitudinal data from New Zealand

Abstract

The overall small, positive, but statistically non-significant, income--health effect size is consistent with similar analyses from other longitudinal studies. Despite the overwhelming consensus that income matters for health over the medium and long-term, evidence free of time-invariant confounding for the short-run association remains elusive. However, measurement error in income and health has probably biased estimates towards the null.

Do changes in socioeconomic factors lead to changes in mental health? Findings from three waves of a population based panel study

“…Our finding of no effect for income is consistent with other studies that have used panel data and random or fixed effects11 14 and with our own previous work looking at self-rated health 32. However, some studies have found a relationship between income and general MH but for women only, although the effect size is small 15 16.…”

The impact of in-work tax credit for families on self-rated health in adults: a cohort study of 6900 New Zealanders

“…Because IWTCs concurrently improve income and employment, decomposing the IWTC-on-health effect into income and employment effects is impossible 32. However, regarding the potential causal pathway through income, the current study findings are consistent with international13 and NZ14 evidence of no short-term effect of changes in income on SRH. Regarding the employment pathway, the null-findings are plausible if IWTC principally moved individuals into employment that is insecure or with negative working conditions.…”

“…Previous evidence of IWTC improving smoking19 (also in Whites/Hispanics)18 in the USA and life satisfaction in the UK,14 compared with the null-findings for SRH in NZ, if not due to improvements in the former health outcomes not translating into improved SRH,14 could be explained by differences in IWTC designs, such as NZ's IWTC universally covering low-income and middle-income groups, whereas those in the USA and the UK exclusively target low-income families. Furthermore, if the broad welfare state provision of public health and social services fulfil the basic health needs for low-income and middle-income families in NZ, but these needs are not equally met by the lower safety nets provided to low-income families in the USA/UK, then additional income from IWTC should impact health less in NZ than in the USA/UK.…”

“…)11 In short, regarding the income pathways (A-B and C-E-B in figure 1), parents spend additional income from IWTCs, which may lift incomes above the minimum for healthy living,12 on health-promoting, but also health-damaging goods and services for themselves and/or their children 11. A recent systematic review13 and research from NZ14 found that increases in income had no discernible short-term effect on self-rated health (SRH), suggesting that the income-to-health pathways may not be strong. Regarding the employment pathway (C-D), the health effect of moving into employment depends on whether the employment is stable or insecure15 and working conditions positive or negative 16.…”

“…Regarding the employment pathway (C-D), the health effect of moving into employment depends on whether the employment is stable or insecure15 and working conditions positive or negative 16. However, research from NZ suggests that employment causally affects SRH,14 making employment a viable mediator for any IWTC-on-health effect. Finally, the evidence of a direct effect (F) of IWTCs on health is mixed 11.…”