Reddit has approximately 542 million monthly visitors and is ranked the 8th most visited site on the global Internet and 4th in the US 41. AskReddit, with approximately 18.4 million subscribers, is a sub-forum where any user may post a question for general advice, openended discussion, or lived experience. Users may reply to the question or to other users' replies. Forum rules forbid posting identifying information and users post under a chosen username or create a one-use 'throwaway' account. Users may vote on comments as part of a wider 'karma' system. 'Up-votes' contribute to karma while 'down-votes' take from it, with 'up-votes' generally taken as agreement with the comment or as an expression of respect for or empathy with the poster. Griffiths 42 cites several factors supporting Internet collected qualitative data; easy access to wider recruitment, a potential global sample population, cost-effectiveness, reduction in social desirability, data in common digital formats, and accessibility for those uncomfortable with in-person participation. This allows a vulnerable population complete control over their environment and comfort level, avoiding social pressures and self-stigma. Evidence suggests individuals with schizophrenia exhibit Internet use behaviour comparable to a non-clinical sample 43 , incurring no additional risks participating in online research. In this study, reddit users were free to ignore the posed question, thus those who commented truly wanted to share their experiences.

Purpose It has been proposed that parents should be educated about child autistic spectrum disorder (ASD) 'red flag' traits to help professionals identify and address concerning behaviours as early as possible. This study aimed to empirically demonstrate that established/recognised 'red flag' traits in the first 3 years of life would reliably predict ASD risk severity in later childhood, associated with established ASD risk correlates and mirroring functioning diagnostic categories. Methods Using retrospective parental report data from the Mental Health of Children and Young People in Great Britain survey (N = 7977), latent class analysis (LCA) and a quasi-latent transition analysis were used to (1) identify profiles of variation in parent reports of child 'red flag' traits before and after age 3 and (2) model transitions in risk from 3 years and below to ≥ 3 years, respectively, per the 'optimal outcome' model. Results Three distinct classes, each characterised by variation in parent 'red flag' trait reporting were identified for the '≤ 3 years of age' and the '≥ 3 years of age' data. Both LCA class profiles comprised groups of children characterised by low, medium and high ASD risk. Dose-response effects for a number of recognised ASD correlates across the low, moderate and high risk '≥ 3 years of age' classes seemed to validate older classes in terms of ASD relevance. Over 54% of children characterised by the highest levels of ASD 'red flag' trait probability at 3 years and below (2% of sample), also populated the high-risk class evidenced in the '≥ 3 years of age' LCA. Conclusions Retrospective parental reports of child ASD 'red flag' traits ≤ 3 years of age were reliable indicators of ASD risk in later childhood.