1. Waldman et al, 2006, “Does Television Cause Autism” Presented by Joseph Guse for Econ 398, Fall 2010 (revised, Fall 2012)

2. Autism Symptomatic Definition. – Impaired language development (not Aspergers) – Social interaction impairment, Mind-blindness – Obsessive and Repetitive Behaviors Need for stability and predictability – Symptoms apparent by age 3. – 4X more common in boys Etiology – Genetic – Home Environment – Physical Environment – Genetic with Environmental Triggers What is it really? Competing theories – Attention Disorder – Executive Function Disorder – Mind-blindness

3. Autism Trends 1970: 1 in 2500 1992 – 1999: 400% increase – Probably due in large part to DOE reporting which started in 1991. 1999 – 2003: Doubled Again! 2005 Rates in Sample CA:.0018 OR:.0068 WA:.0023

4. Somali Immigrant Clusters NYTimes, March 16, 2009 Minneapolis: 25 percent of the children in preschool classes [for autistic children] are Somali, while only 6 percent of public school enrollment is Somali. Stockholm: Somalis were in classes for autistic children at three times the normal rate. “ The city is welcoming and social benefits are generous, but many live a life apart as conservative Muslims, the women in head scarves and long dresses.” “People are so isolated in their apartments here.”

5. Competing Theories on Trend and Causes Not happening. – DOE reporting – Diagnosis. (criteria broadening, classification) Vaccines. (Mercury) Vitamin D. Warnings about skin cancer Air Pollution Television

6. Anecdotal Evidence that (1)It really IS happening (2) It could be TV. California Data. Been keeping data since 1969 at 21 regional developmental disorder centers. – 1980 cohort has double rate as 1970 – 1986 cohort has double rate as 1980 – Relationship with Trends in Video Exposure Attention Deficit Disorder. 1 hr TV -> 10% increase in Prob(ADHD). Reverse Causality? Behavior of “High Risk” Infants. Failure to disengage from dynamic colorful images. Amish. Should be hundreds of cases among the Amish in PA, if they experience the same hazard rate. But there fewer than 10 cases. They don’t watch TV. (Of course, they have very different lifestyles in many ways.)

9. Empirical Strategy I Precipitation as Exogenous Variation IV Approach: Precipitation – Use ATUS to establish that precipitation and TV exposure are correlated – Run various regressions of Autism rates on Precip. Advantage: Positive correlation cannot be explained by reverse causality: Autism most likely does not cause rain and snow.

10. Data for Part I.i Establishing link between weather and TV viewing. Precip Data: raw data is from daily weather data from the National Climactic Data Center’s 8000 weather stations across the U.S. – Use avg across all stations in county linked to observation in the ATUS. TV Watching: 2003 ATUS

11. “First Stage” Regression Didn’t really do 2SLS or even 2-Sample 2SLS, but you get the idea… NOTE: THIS IS ONLY A PORTION OF AUTHORS’ Table 2

12. Data for Part I.ii Establish link between Precip and Autism Focus on Three States (CA, WA and OR) with high precip variability. Most convincing specs: – OR: county-level age-specific autism rates in 2005 for children born between 1987 and 1997 – CA: County-level birth cohort specific autism rates measured when cohort is 8 y.o.

13. “2 nd Stage” Part 1 2005 Autism Rates and Precip

14. 2 nd Stage Part II: Age-Specific Data

15. Part II: Cable TV Diffusion Data: autism rates for each cohort born between 1972 and 1989 at the county level in CA and PA Avoids satellite era. Cable TV Data source: Television Factbook Drop counties with poor over-air reception Run several specs, including FE (table 7)

17. Doubts may remain Positive Correlation Consistent with several Hypotheses: Author’s basic logic: Precip -> TV -> Autism Could be something else about rainy weather or being indoors and have nothing to do with TV per se. Precip -> Indoors -> REAL CAUSE -> Autism Where R.C. = Low VitD? Indoor Air Quality? Low Exercise? TV Could be further up causal chain: E.G Weather Time IndoorsTV Real Cause Autism

18. Improvements? Two Sample IV More weather variables: cold, heat

19. Critique from a Non-Economist Tee Guidotti (2005) “Evidence of Causation” Archives of Environmental and Occupational Health.