Here we are, witnessing the application of sequence analysis once again in two other contexts. It appears to be a commonly used method in life-course studies!
Sabbath et al. 2015
1. Authors mention that initially there were 6,489 possible work-family-kids trajectories from which common prototypes were derived with sequence analysis, and then they were compiled in 7 clusters. In the context of the magnitude of data reduction, I'm wondering how many prototypes were derived from such a huge number of possible trajectories. I'm also interested what variables were fed to the clustering algorithm -- e.g. was it based on work-family-kids prototypes only or were there other factors that determined clustering of individuals? I'm also generally interested in this 2-step method of data reduction. Particularly, what is the conceptual difference between sequencing and clustering steps? Both seem to have a goal of data reduction.
2. I wonder how generalizable these findings are to more recent age cohorts. The study captures the trajectories of women born in 1935-1956. Given that the norms and culture change over time (e.g. individuals are having fewer children, couples tend to cohabitate rather than marry etc.), we might expect seeing different clusters of work-family-kids trajectories vs. the ones discovered in this study. Because some other trajectories are more common now, and others are more "extinct". This could potentially affect the discovered relationship between work-family-kids trajectories and health outcomes.
3. Due to various adjustments performed in the data analysis stage it's quite clear what contributes to increased mortality in single non-working mothers or single working mothers (e.g. health-related behaviors, SES, education). But it is less clear what drives the increased mortality in married non-working mothers. After adjustment for various factors, the magnitude of association between this trajectory and death remained large. Authors make the argument that work may be very beneficial for health. It would be interesting to investigate this issue further.
Harrati et al. 2019
1. Interesting that in this case the results of sequence analysis (resulting typology) were used as a dependent variable rather than an independent.
2. Last cluster (representing long-term disability leaves) comprises only 1.65% of the sample. I'm wondering if this raises any issues in terms of how confident we are of the results for this particular level of the "outcome". Is this small number of individuals in a cluster or imbalance between cluster sizes problematic?
3. Together with the authors, I'm also very interested why females have more disruptions and short-term disability leaves vs. males, given that potential differences in air pollution exposure or occupation do not explain these disparities. As the authors state, this could be due to selection -- i.e. women working in this manufacturing setting comprise a unique population whose distinctive features may have contributed to these disparities. Would be interesting to investigate this further.