I likely have said one could do this, creating a graph of Newson's cohort size over time. Here you are. First image shows graph use in a powerpoint. Second image is graph by itself. 
This graph is important in current PDA literature due to O'Nions arguing there might be a "collider bias" with Newson's research as an explanation for Newson's PDA looks different to autism.
I would point out the graph shows logic behind a potential "collider bias", that Newson's cohort is nonsense.
Essentially, Newson's cohort was biased by its referrals of complex presentations, Newson's clinic would mainly see those with severe/ high diagnostic threshold for autism, so Newson's cohort is representative of "milder" PDA & autism presentations...
... Thus, Newson's cohort is not representative of what autism spectrum might actually look like...
... Obviously, O'Nions & Eaton fail to consider Newson's clinic referrals, would have included CYP with co-occurring conditions & non-autistic persons. This is a tangent...
Screenshot of full text & logic behind a possible "collider bias" in Newson's cohort. O'Nions & Eaton 2021, p411.
... There are other issues why it is nonsensical to view Newson's cohort as having a "collider bias", such as Newson excluded cases with autism features. Also, how Newson never based PDA on the Triad of Impairment...
Image from Newson et al 2003 p599.
Image from Newson et al 2003 p599.
... "A few children whose clinical picture is less certain, often because of additional autistic characteristics, but atypical of autism also, were excluded." (Newson et al 2003, p 596)...
... Sharp rise in number of cases in Newson's cohort around 1988 is vital.
This likely due:
1) Western recognition of Asperger's Syndrome & expansion of autism spectrum.
2) Common reference point from creation of PDA's first diagnostic profile in 1988...
This likely due:
1) Western recognition of Asperger's Syndrome & expansion of autism spectrum.
2) Common reference point from creation of PDA's first diagnostic profile in 1988...
I discuss these two points in detail here.
rationaldemandavoidance.com/2020/10/17/wha…
rationaldemandavoidance.com/2020/10/17/wha…
... The point is that majority of Newson's cohort was recruited after acceptance "milder" autism cases. Which contradicts fundamental assumption behind why there might be a "collider bias" in Newson's cohort...
... It seems symptomatic of a broader lack of critical engagement with PDA, & asking is it actually a "Profile of ASD". Lack of considering if PDA represents something new, or something else other than autism...
... The differences between PDA & autism in Newson's research is because Newson never conceptualised PDA as a "Profile of ASD", Newson's methodology & that PDA seems to represent a distinct clustering of features which is different to autism...
... "“hanging together as an entity” is not enough if that entity is not significantly different from both autism and Asperger’s syndrome, either separately or apart," (Newson et al 2003, p599)...
... Newson literally tells us that PDA needs to be different to autism spectrum. Likewise PDA is not ASD. & it would be a mistake to view PDA as an ASD...
... "PDA is a pervasive developmental disorder but not an autistic spectrum disorder: to describe it as such would be like describing every person in a family by the name of one of its members." Newson et al (2003) supplementary notes...
... Newson's comments about PDA traits needing to be different from autism & not just hanging together, is important, as it Newson saying PDA seemingly being present in many persons is not evidence to support PDA being a thing...
... i.e., just because there are X thousands of persons in social media groups would not be evidence PDA being a "thing" due to its strong recognition factor (yes I know Newson wrote her article before social media was a big thing)...
... The point about PDA seemingly represents a different clustering of features than autism is seen throughout her diagnostic groupings, NOT having PDA clustering with autism, or based on triad of impairment...
... Even how O'Nions initially recognised PDA was mainly constructed of many non-autism features. Which uncoincidentally includes anxiety as not being a feature of autism...
Image from O'Nions 2013, p93.
Image from O'Nions 2013, p93.
... There are more than enough indicators in PDA literature that inform the notion is not sensible to view PDA as a "Profile of ASD". Hence, why I say it seems to be a lack of critical engagement with PDA & asking if it might be something other than autism...
... There are MANY more indicators in the PDA literature which support notion it is not sensible to view PDA as a "Profile of ASD" than given in this thread.
I will bring this thread to a close...
I will bring this thread to a close...
This graph on how Newson's cohort size grew over time is important in dispelling the notion there might be a "collider bias" in its research, from over representation of high diagnostic threshold cases.
Link to Newson et al (2003) with it supplementary material.
adc.bmj.com/content/archdi…
adc.bmj.com/content/archdi…
Link to O'Nions & Eaton (2021).
paediatricsandchildhealthjournal.co.uk/article/S1751-…
paediatricsandchildhealthjournal.co.uk/article/S1751-…
@threadreaderapp please could you unroll again?
Thank you in advance.
Thank you in advance.
... Just a quick addition to this thread. We know that Newson's clinic did receive a range of autistic persons. From Newson's Study B, including 20 CYP with Autistic Disorder & 20 CYP with Aspergers...
Screenshot describing Newson's Study B, from Newson 1998.
Link to Newson (1998). with their Study B described.
autismeastmidlands.org.uk/wp-content/upl…
autismeastmidlands.org.uk/wp-content/upl…
... Screenshot is important as it states that sample for Study was collected from November 1987 to February 1996. Which is almost exactly from the 1988 increase in Newson's PDA cohort had a sudden increase...
... The point is that I do seem to be correct that it is nonsensical to view Newson's PDA cohort having a "collider bias" from being biased due to mainly having PDA or autism cases with a severe presentation/ high dx threshold...
... Newson (1998) also has interesting information on gender ratio in Autistic Disorder & Asperger's groups, of 19:1 males to females; there is a substantial male bias present...
... The 20 Autistic Disorder & 20 Asperger's cases were randomly selected, so can be considered likely representative of gender ratio of Newson's autism spectrum disorder cohort...
... Which then casts further doubts that Newson's cohort has an over representation of autistic females as argued in Bishop (2018)...
... It does seem to be correct about a lack of critical engagement with assuming PDA as a "Profile of ASD" is an issue with those conducting PDA research.
On that note. I will end this thread again.
On that note. I will end this thread again.
@threadreaderapp please could you unroll again?
Thank you in advance.
Thank you in advance.
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