Wednesday, February 16, 2011

Curebie Attitudes in Mothers and Autism Severity

Neurodiversity advocates always get this particular comment: 'But what about severe autism? How could you see it as part of diversity?' In my research into correlates of curebie vs neurodiversity attitudes in mothers of autistic kids, this raises an obvious question - how does the child's severity of autism interact with the mother's perspective on autism?

I focused more on the parent than the child in my research, but I did ask three questions that could be considered markers of autism severity - child's diagnosis, child's level of verbal skills, and whether the child had 'significant behavior problems'.

Child's Diagnosis

One mother didn't report the child's specific diagnosis. Of the others, 4 (27%) of the children had Asperger Syndrome, 5 (33%) had PDD NOS, and 6 (40%) had Autism.

I ran an ANOVA by diagnosis for curebie/neurodiversity, self-esteem, depression and parental stress. Only curebie/neurodiversity correlated with the child's diagnosis, at a significance level of .034. Parental stress was almost significant at .058.

The post-hoc tests revealed a significant difference between Asperger Syndrome and Autism - parents of Asperger Syndrome children were more likely to endorse a neurodiversity viewpoint than parents of children diagnosed with Autism. PDD NOS did not significantly differ from either group, they appeared to be intermediate between both groups.

So, this would seem to support the hypothesis that parents of more severely-affected children had more curebie attitudes.

Verbal Skills

I had the mothers rate their child's verbal skills on a five-point scale - normal, delayed but communicative, echolalic, limited speech (eg single words) or nonverbal.

When I first ran the ANOVA, it failed to perform any post-hoc tests due to insufficient sample size in at least one group. On closer examination, I realized only one child was rated as 'limited speech'. This child with 'limited speech' was 2 year 8 months old, the youngest in the sample, suggesting that this child should be better considered 'delayed but communicative'. I lumped that child in with the nonverbal children and re-ran the ANOVA with four groups: normal speech (3 children), delayed communicative/limited speech (6 children), echolalic (5 children) and nonverbal (2 children).

The ANOVA failed to find any significant difference by verbal skills in parents' attitudes towards autism, self-esteem, depression or stress levels. None of the p values were anywhere close to significant, so this is probably not due to small sample size (though I can't be certain unless I redo this study with more subjects).

This is interesting, because it seems to contradict the results by child diagnosis. One of the biggest determinants of whether a child is diagnosed with Autism or Asperger Syndrome is their verbal skills. In the DSM-IV, Asperger Syndrome requires no significant delay in verbal skills. Autism doesn't technically require verbal delay, but it does require abnormalities in verbal communication, and verbal delay counts towards an autism diagnosis.

When I ran an ANOVA of the relationship between child's verbal skills and their diagnosis, the p-value was .085, which barely missed significance. The Asperger Syndrome kids included the child with 'limited speech', one echolalic child, and two with normal verbal skills; the PDD NOS kids included one echolalic kid, 4 delayed but communicative kids and one with normal verbal skills; and the Autism kids included 2 nonverbal, 3 echolalic and one delayed but communicative. So there was clearly a trend for poorer verbal skills in the more 'severe' diagnoses, but also a certain amount of within-group variability.

I split the file by child diagnosis and re-ran the ANOVA by verbal skills. The only significant finding was in the Autism group, where parental stress correlated with verbal skills. In order to run post-hoc tests on that, I had to lump the one 'delayed but communicative' kid in that group with the echolalic kids. However, when I did that, the significance disappeared. Not sure what that means. In any case, it's clear that when controlling for child's diagnosis, there was no relationship between their mothers' perspective on autism and the child's verbal skills.

This suggests that whatever it is about child's diagnosis that relates to their parents' perspective on their autism, it's not the child's verbal skills. Maybe the different conditions have different stereotypes associated with them, maybe their diagnosis reflects differences between the kids that I couldn't measure, or maybe the parents reported the child's diagnosis differently depending on their own perception. (For example, I've heard anecdotal reports of the same child receiving different autism spectrum diagnoses from different professionals. In such a case, the parent may be more inclined to believe the diagnosis that best reflects how they view the child.)

Significant Behavior Problems

The question on 'significant behavior problems' was an open-ended question where parents filled in a comment box. Each parent's response was analysed both to determine whether they said 'yes' or 'no' to the question, and which behaviors they reported.

It's important to keep in mind that this is a very subjective question - each mother likely had her own definition of 'significant behavior problems', and the availability heuristic could easily affect reports of behavior problems. So different responses could reflect actual differences in the children's behavior, differences in parental definitions of behavior problems, or differences in how easily the parent called to mind the child's behavior problems.

Two parents left this question blank. Of the remaining mothers, 10 (71%) answered yes and 4 (29%) answered no. Specific behaviors listed were mood problems in 8 children, aggression in 6 children, atypical behaviors (eg laughing out of sync with surroundings, pica) in 3 children, crying in 3 children and self-injury in 2 children.

I ran a T-test for behavior problems and each of the four parent variables. Self-esteem showed no significant associations. Depression had significantly higher variance in the 'no' group (p=.013) than the 'yes' group, but mean rates were no different. Both parental stress and curebie/neurodiversity attitudes correlated significantly with behavior problems - 'no' answers indicated more neurodiversity attitudes and lower stress.

This confirms previous research on parental stress in autism, such as Konstantareas & Homatidis (1989), who found that self-injury and irritability in autistic kids were the best predictors of their mothers' stress levels. This is generally interpreted as parents being stressed out by difficult children, though it's also possible that the parent's stress makes the child's behavior worsen - I know I often have a meltdown when my parents are already upset about something else.

Tuesday, February 15, 2011

Words, Triggers and Political Correctness

A lot of people criticize political correctness, saying 'it's just words' and accusing proponents of trying to change speech without changing attitudes - or of naively thinking that attitudes will automatically change along with speech. Meanwhile, proponents of political correctness argue that words do matter, that certain words are hurtful to the people they're applied to, and that use of certain insults follows from and reinforces certain attitudes.

I think I have an idea of part of what underlies this. It's triggers.

Here's a hypothetical kid, named Timmy. Timmy was born with Down Syndrome.

His parents were told to institutionalize him at birth because 'retards destroy families'. They got angry and replied that he was their child and they loved him, and resolved to raise him the best they could.

When he was 6 years old, they tried to enroll him in the neighborhood school, the same school his older brother went to. The school refused him entry. 'We're teachers, not babysitters. Send him to a school for retarded kids.' The parents were angry, but they couldn't change the school's decision, so they sent Timmy to a special school.

Throughout his school years, Timmy would board the special bus that only disabled kids rode on, and neighborhood kids would laugh and point, saying 'look at those retards'. One time, he told them off for laughing at him, and they made fun of his Down Syndrome speaking style and told him that he talked like a retard. Timmy was so upset by this that he couldn't say anything at all.

At school, some of the teachers were nice, and others weren't so nice. The nice teachers were patient and encouraging, and seemed to enjoy spending time with him. The mean teachers tried to hurry him and got mad when he struggled, and talked among themselves about how annoying the retards they taught could be - often forgetting or overlooking that Timmy was within earshot of them as they said this.

One day, Timmy's brother came home in tears, because some of his classmates had made fun of him for having a 'retarded brother'. At first he was outraged and hurt, but he still felt the need for friendship, so gradually he stopped inviting Timmy along when he went out with his friends, and stopped inviting his friends home to meet his family. And sometimes, in order to gain acceptance, he'd laugh along with his friends when they made a joke about a 'retard', inwardly apologizing to Timmy when he did so.

Now Timmy's grown up, and he's become a self-advocate. He's arguing against institutionalization, advocating mainstreaming, speaking out against bullying, telling teachers to be patient and kind when teaching kids like him. And whenever he hears the word 'retard', he hears it echoing from the mouths of everyone who discriminated against him and hurt him. He remembers being a kid with speech problems trying to stand up for himself and getting viciously shut down, remembers anticipating walking to school with his brother and ending up taking a special bus instead, remembers feeling ashamed and frustrated when the teachers pushed him too hard and got mad at him for failing, remembers all the painful moments in his childhood when someone used that word.

My Dad is very good at imitating accents. Once, he bragged to a black South African that he could do an Afrikaans accent, and the guy said 'OK, let's hear it'. My Dad replied, in an Afrikaans accent: 'State your name, kaffer.' (The phrase that most easily came to mind in that accent.) The black guy flinched, my Dad apologized, and he shrugged it off and told my Dad that he'd done a very good job of imitating the accent.

Being the target of discrimination is a traumatizing experience. If you read the literature on PTSD, you'll find that anything that is associated with a trauma can set off painful emotions. I read of one woman who felt anxious when someone stood on the other side of her closed bedroom door - the sight of their legs disrupting the bar of light under the door made her afraid. As a child, her father used to come to her bedroom at night and sexually abuse her, and his legs behind her bedroom door became a signal of impending abuse.

Some derogatory words, such as kaffer (heathen) or faggot (wood for a fire), are derogatory in etymology, whereas others such as nigger (black) and retard (slow) are not. I know one guy who calls himself a 'slow learner', while opposing the word 'retard'. I wonder if he realizes that those two terms mean exactly the same thing. But it doesn't matter what they literally mean, I suppose. What matters is the feelings associated with them - pain and shame with 'retard' and self-advocacy with 'slow learner'.

On the other hand, some people don't have those associations. Some black people have only ever been called 'nigger' by playful black friends, so the word has playful teasing associations rather than hateful ones for them. Others have made a conscious choice to break apart those negative associations, to refuse to allow prejudiced people control over the usage of that word. If you reclaim something, it'll often lose its sting.

But keep in mind that words have emotions linked to them. If you use the wrong words, you'll scare and hurt people by bringing up pain from the past. In my self-defense class, I learnt moves to stop people from choking me. On the following weekend, I was practicing these moves with Dad, and Mom (who was choked as part of childhood abuse) told me to stop. I obeyed. I didn't think there was anything wrong with my Dad choking me with my permission, ready to stop as soon as I needed him to, but I recognized that doing that in her presence made her feel unsafe. For the same reason I didn't practice choking defense in front of Mom, I don't think you should use words like 'retard' and 'nigger' in front of people likely to be upset by them. I don't think those words are inherently banned, but you should be sensitive to the context.

Now, saying those words are fine isn't saying the attitudes that have gotten linked with them are, any more than saying it's OK for me to be consensually choked in self-defense practice is saying it's OK to choke a child abusively.

Monday, February 14, 2011

Curebie Attitudes and Coping in Mothers of Autistic Kids

A long time ago, I wrote a survey for parents of autistic kids to fill out. I got 16 respondents, all mothers. Back then, I didn't have access to SPSS, but I did some stats on my own. Unfortunately, the results were lost when my website disappeared.

Anyway, I've dug out the data again, and now I'm running it through SPSS to test various hypotheses.

Firstly, a basic description of my data:
  • some demographic questions (where do you live, what's your ethnicity, what's your religion, what other parents does your child have, how old is your child, what's their diagnoses, when were they diagnosed, do you have any other kids, are they disabled, do you think you're on the spectrum, etc)
  • if they suspected their child's diagnosis, why, how good their child's verbal skills were, whether their child had a lot of behavior problems, and what therapies their child had gotten and how helpful they were
  • some qualitative questions about how they were affected by the child's diagnosis, how they thought the child perceived their own condition, how they wanted their child to perceive their condition, and what they thought caused autism
  • Likert-scale questions about self-esteem (borrowed from some old study that I can't seem to find now)
  • Likert-scale questions about parental stress (a reworded version of some questionnaire where every question started with 'I need' or 'my family needs')*, scaled so higher scores represent lower stress
  • Likert-scale questions about parental autistic traits
  • Likert-scale questions about the DSM-IV symptoms of depression
  • Likert-scale questions about curebie/neurodiversity attitudes towards autism (this one was the only one not adapted from somewhere else)
I'll do other analyses at other times. But right now, I'll focus on my curebie/neurodiversity questionnaire and how it correlates with parental well-being (self-esteem, depression and stress).

Scale Reliability

If a scale is measuring a single underlying construct, then the items should be correlated with each other. The test for inter-item correlation in a scale is called 'Cronbach's alpha', and the higher this number is, the better the scale is.

I ran Cronbach's alpha on the 17 questions in this scale, and it spat out a value of .894 (the score ranges from 0-1, so this is very good). I noticed that it had excluded 10 cases based on them not having data for all the questions, so I removed one question ('my child's behavior makes sense to me') which I'd added partway through the study and therefore didn't have full data on. The next Cronbach's alpha was .802, and all 16 cases were included in that analysis.

Then I ran bivariate correlations to see if the questions were correlated with the summed score (with higher scores meaning neurodiversity attitudes, incidentally), and found the following for each question (* means p=<.005 and ** means p=<.001, reverse scored means that 'strongly disagree' counted higher than 'strongly agree'):
  • I feel despair when I think of my child's future (reverse-scored) -- .875**
  • If my child's autism is not cured, he/she will have to be institutionalized (reverse-scored) -- .560*
  • I often think my child would be better off dead (reverse-scored) -- .612* (note: all parents chose between strongly disagree and neutral on this question and the next one, none agreed)
  • I have seriously considered killing my child (reverse-scored) -- .468
  • I don't think there is anything good about autism (reverse-scored) -- .408
  • I would rather my child have leukemia than autism (reverse-scored) -- .562* (all parents chose 'disagree' or 'strongly disagree' on this question)
  • I get very sad when I see a typically developing child who is the same age as my child (reverse-scored) -- .693**
  • I think of my child as trapped inside autism (reverse-scored) -- .687**
  • I often feel like I have lost my child (reverse-scored) -- .532*
  • There is a conspiracy to keep parents from knowing the true cause and/or cure of autism (reverse-scored) -- .313
  • I worry that my child hasn't got enough therapy at a young enough age (reverse-scored) -- .666**
  • My child has a lot in common with me -- .619*
  • Autism is not a big part of who my child is (reverse-scored) -- -.312
  • Autism is not really a bad thing, it just means you are different from the norm -- .484
  • I think of myself as a warrior fighting against autism on my child's behalf (reverse-scored) -- .575*
  • I think of myself as a warrior fighting against society (for example, the school system) on behalf of my child (reverse-scored) -- .555* (note: I originally planned this to be positively scored, but I noticed that it correlated extremely strongly with 'war on autism')
It's a bit disappointing how many of the questions weren't significantly correlated with the total score, though that could've been due to small sample size.

However, the one question that actually showed a (non-significant) negative correlation, 'autism is not a big part of who my child is' (reverse-scored), was interesting. Although many neurodiversity autistic self-advocates (myself included) argue that 'autism is part of who we are, not a condition we have', it seems like most parents who see autism as a big part of their child do not have a positive view of the condition. This question correlated significantly with despair at the child's future, expecting the child to be institutionalized, feeling like they'd lost their child and being at war with autism. So it seems like 'person-first' advocates might actually have a point - some parents seem to view autism as an engulfing monster that has taken over their child.

I could switch that question to being positively scored, or else reword it as something like 'you can't separate my child's autism from his/her basic personality' or 'if my child's autism were cured, he/she would be a different person', which might better tap the neurodiverse sense of autism as part of identity. Ideas for further research!

Curebie/Neurodiversity and Parental Well-Being

(Note: The self-esteem scale had a Cronbach's alpha of .835, the parental coping scale had an alpha of .678, and the depression scale had an alpha of .834.)

I ran bivariate correlations between curebie/neurodiversity, depression, parental coping and self-esteem. The curebie/neurodiversity questionnaire was strongly negatively correlated with depression (-.603, p=.023), positively correlated with parental coping (.830, p<.001) and uncorrelated with self-esteem (.392, p=.148). Depression was also negatively correlated with self-esteem (-.694, p=.004), which is consistent with pretty much any study into depression and self-esteem. But neither depression nor self-esteem were correlated with parental coping.

Given that my depression question were grabbed from the DSM-IV, I was interested to see how many met criteria for a major depressive episode. The cut-off is 5 or more, including depressed mood and/or loss of interest (criteria 1 and 2). I decided to take agree or strongly agree as indicating presence of a symptom. (Note: Diagnosis-by-questionnaire is not an accepted clinical diagnosis, but it is commonly used in the literature to approximate a diagnosis.)

Based on this criteria, 4 parents were depressed and 10 weren't depressed (2 didn't answer all the depression questions and so were excluded). This means 29% were depressed.

Then I ran a T-test on neurodiversity/curebie, self-esteem and parental coping between depressed and non-depressed parents. Self-esteem scores were the only significant difference between the two groups, at (p=.013). This might be due to small sample sizes (4 is a very small number for statistical analyses).

* In retrospect, I shouldn't have reworded the questions, because even slight changes in wording can affect people's responses.

Thursday, February 10, 2011

I Just Want Him To Be Safe

[Update: Mom says the school responded very well to her concerns in a parent-teacher meeting. They said they will talk to the gym teacher and insist that he find other methods of encouraging my brother to be physically active, saying that it's inappropriate to punish the entire class for one student.]

My family is currently living in two separate towns for work-related reasons. My mother and 13 year old brother are in one town, while my father and I are in another.
Yesterday morning, my brother called us in tears. It turns out that the day before had been a very bad day at school. My brother is a big boy, built like a football player, and slightly chubby. He's also not much into physical activity, and not very well coordinated (though far better than I am).
He's told me about his gym teacher drinking protein shakes and giving them lots of fitness advice. The same teacher is also his science teacher, and tends to spend an awful lot of science class teaching about the body. He seems to be completely obsessed with being fit.
Anyway, the day before yesterday, they were running laps in gym. My brother is not a good runner and never will be, because of his build. And this class, he was the slowest and the first to tire. His gym teacher decided to keep everyone running laps until my brother made it through an entire lap without needing to stop. Of course, this was a losing battle, given that the more you push yourself, the more tired you get. My brother eventually ended up lying in a fetal position on the ground, too tired to move. At this point, most of the rest of his class started taunting him, and the teacher praised them for 'encouraging' him.
Another thing about my brother: he is extremely sensitive. He's one of the most caring kids I've ever met. He is very much a people-pleaser, and unlike me, he often doesn't stand up for himself. He is the one in my family least likely to show anger when I have a meltdown, even if it was a conflict with him that set it off. I have to be careful when I ask him for favors because he has trouble saying no to me.
My brother is typically the first one to come home, since his school lets out before Mom's work does. This day, he came home extremely upset. Apparently he kind of trashed the place, for example smashing a piece of fruit on the ground. Then he went on World of Warcraft and talked to people in the guild some of his characters belong to, and they comforted him. (An aside: Video gamers are stereotyped as socially isolated, but for many people, multiplayer video games put them in contact with some great friends they'd otherwise never have met.)
Now my Mom's going to have a meeting with the school, hoping to sort something out, but I don't know if anything will come of it, given how resistant schools are to criticism. Meanwhile, I'm feeling worried. My brother had a lot of school problems last year, and he's having problems this year too. He's been getting down on himself a lot lately - a couple weeks ago he was criticizing himself for being late to school. (He walks to school, and my Mom leaves before him. If he arrives early, he has to wait in class without anything to occupy himself, so he leaves at the very last moment. I suggested he bring along paper and a pencil, because he likes to draw. But the big problem there wasn't his lateness, but his reaction to it.)
I keep thinking about myself, when I was just a year or two younger than he is now. I understand that he's not me, and isn't having nearly as much trouble as I did. But I wonder how much he just keeps inside, rather than telling us. I wonder if he's going to loose sight of happiness the way I did. And I desperately want to protect him from that - but I'm not his parent, just his big sister.

Wednesday, February 02, 2011

Behavior in Four Chromosomal Syndromes

On the Trisomy 9 Website, run by the mother of a little boy with partial trisomy 9p, there is a survey. A few years ago, she used to provide the full data set of the survey as well as the results. Back then, I downloaded a copy of it, and now that I have access to SPSS, I've decided to analyze the results myself.

I'm focusing on the subsection regarding behavior ('habits'), because I'm fascinated by behavioral phenotypes. There are many different kids with different conditions described in the survey, but I'll focus on the four most common syndromes - trisomy 13, trisomy 18, partial trisomy 9p, and mosaic trisomy 9. I took all the kids within those four groups (11 with trisomy 13, 16 with trisomy 18, 25 with trisomy 9p and 8 with mosaic trisomy 9) and analyzed their survey results for behavior.

Factor Analysis

The first thing I did was to run a factor analysis (well, actually, the first thing I did was to recode 'yes' as 2 and 'no' as 1, then I did the factor analysis). I don't really know factor analyses that well, so I may have screwed up stuff. If you know enough about factor analysis to spot a mistake I made, let me know.

I found 10 factors. Here they are, with correlations greater than .3 listed:
  • factor 1: chews on toys (.696), dances (.643), chews on clothes (.588), touches everything (.573), stubborn (.561), tantrums (.550), throws head back (.543), throws objects (.503), shows no fear of falling (.438), bites self (.436), tenacious (.432), rubs hand across face (.411), great memory (.400), kicks feet (.381), loves mirrors (.349), affectionate (.325), must hold something (.307) and loves baths (.303)
  • factor 2: great memory (-.714), rocks/shakes head (.663), hates eating (.636), kicks feet (.536), throws head back (.520), sucks finger/thumb (.477), dances (-.460), loves eating (-.449), rubs hand across face (.411), drools (.384), very happy (-.378), tenacious (-.365), stubborn (-.353) and must hold something (-.346)
  • factor 3: drools (.608), sucks on finger/thumb (.517), loves music (.445), very happy (.444), loves eating (.430), socializes (.405), stubborn (-.399), bites self (.346), kicks his/her feet (-.342), throws objects (-.339), chews on clothes (.316), tantrums (-.313) and rocks/shakes head (.312)
  • factor 4: very happy (.598), dislike solitude (.446), loves mirrors (.441), throws objects (.435), rubs hand across face (-.407), tenacious (-.382), grumpy (-.362), socializes (.352), loves baths (.326), throws head back (-.322) and touches everything (.321)
  • factor 5: high pain threshold (.697), no fear of falling (.485), loves mirror (-.422), grumpy (.343), loves music (-.340), tenacious (.322), socializes (.314) and bites self (-.302)
  • factor 6: loves music (-.589), bangs head (.528), tantrums (.384), touches everything (.363), hates eating (-.350), no fear of falling (-.330), loves eating (.314) and high pain threshold (-.311)
  • factor 7: affectionate (.617), loves baths (-.608), grumpy (.433), dislikes being alone (.380) and socializes (.331)
  • factor 8: tenacious (.428), drools (.387), touches everything (-.380), grumpy (-.312), throws head back (.303) and tantrums (.302)
  • factor 9: bangs head (-.590), dislikes solitude (.462), loves mirrors (-.336) and affectionate (-.328)
  • factor 10: loves mirrors (-.466), grumpy (-.408), must hold something (.394) and rubs hand across face (-.302)
Hard to say what most of those factors mean, though I'm guessing that factor 1 is related to hyperactivity, factor 3 might be hyposensitivity and factor 4 is probably cheerfulness.

Anyway, I was interested in two main questions: do children with different syndromes behave differently, and is there an age-based difference in behavior? (The kids ranged from newborn to 30 years old, with no significant difference in age between syndromes.)

Syndrome differences

I ran an ANOVA for each factor related to syndrome. The ANOVA indicated that most of the factors weren't significantly associated with syndrome category, but factor 2 was (p=.001). On the post-hoc tests (Tukey HSD, Scheffe and Bonferroni), this turned out to be due to a significant difference between trisomy 18 and trisomy 9p. Trisomy 18 scored the highest on this factor and trisomy 9p scored the lowest, with the other two in between.

I then ran ANOVAs on the specific behaviors with a loading of at least .3 on factor 2, and found significant effects for 'rocks/shakes head' (p>.001), 'must hold something' (p=.026), 'dances' (p=.025), 'stubborn' (p>.001), 'tenacious' (p=.031) and 'great memory' (p=.002). The post-hoc tests (same as above), showed the following:
  • rocks/shakes head: T-13 > T-9p, T-9mosaic; T-18 > T-9p - so trisomy 13 kids were most likely to do this behavior, followed by trisomy 18 kids, then mosaic trisomy 9 and lastly trisomy 9p kids
  • must hold something: oddly enough, no differences were significant, but trisomy 9p was approaching significance with all three other groups. So, they might be less likely to engage in this behavior than the other three groups*
  • dances: T-9p > T-18 - partial trisomy 9p kids were more likely to dance than trisomy 18 kids
  • stubborn: T-13, T-9p, T-9mosaic > T-18 - trisomy 18 kids were significantly less stubborn than the other three groups, who didn't differ from each other
  • tenacious: T-9p > T-18 - partial trisomy 9p kids were more tenacious than trisomy 18 kids
  • great memory: T-9p > T-18 - partial trisomy 9p kids seemed to have better memory skills than trisomy 18 kids
Age differences

This was trickier, since there were so many individual values for age. Mean age was 7.36 years, with a standard deviation of 8.165 years. I got it to tell me the 20th (2 years), 40th (3 years), 60th (5 years) and 80th (13 years) percentile, and used those to generate a categorical variable for age - <2.5 years, 2.5-3 years, 3-5 years, 5-13 years and >13 years.

I then ran an ANOVA on the different factors with age. Like the trisomy ANOVA, this one found that only factor 2 (p=.011) showed a significant correlation. The post-hoc tests found that 2.5-3 year olds scored significantly higher (p=.046) on factor 2 than >13 year olds did. (The plot of means shows high scores for the two youngest groups and a steady decrease for the three older groups.)

I then ran ANOVAs on the specific behaviors with a loading of at least .3 on factor 2, and found significant effects for 'throws head back' (p>.001), 'hates eating' (p=.006) and 'rubs hand across face' (p=.022). The post-hoc tests showed the following:
  • throws head back: under 2.5 > 5-13, over 13 - this behavior was most common in children under 2, and uncommon in kids 5 or over.
  • hates eating: 2.5-3 > under 2.5, 3-5, 5-13, over 13 - this behavior peaked around 2.5-3 years
  • rubs hand across face: under 2.5 > 5-13 - this behavior was common in very young children, rare in 5-13 year olds, and moderately common both in 3-5 year olds and over 13 year olds.
It's interesting that, though both age and trisomy were related to factor 2, they were related to different behaviors within this factor. Unfortunately, I haven't figured out how to do a two-way ANOVA in SPSS yet, so I don't know if different trisomies show a different age-related pattern.


I posted a previous blog entry regarding my adventures with SPSS, where I tested whether wheelchair bowling is easier than regular bowling. I have recently corrected a mistake I made in that post - larger sample sizes should have smaller standard deviations, not larger.
* It spat out an error message saying "The group sizes are unequal. The harmonic mean of the group sizes is used. Type I error levels are not guaranteed." Type 1 errors are finding something when nothing is there, so that might explain why the ANOVA claimed a significant difference that the post-hoc tests failed to confirm.