Lecture 8

• Inside fence: inside information, shared freely within fence
	○ Crypto community including Proto-NSA, technological community including Bell Labs, Bletchley Park
	○ Includes those outside gov in US, but not those outside gov in UK
	○ Not trying to publish things & not listing affiliations
• Outside fence: public domain, Bayesian in general

• Frequentists (old school) vs. Bayesians (new school)
	○ Freedman: "Some Issues in the Foundation of Statistics"- objectivists (Frequentists) vs. subjectivists (Bayesians)
		§ Discusses model validation
		§ Basic problems in applying statistical models to social phenomena

• Remember Wallach's 3 uses of data: statistics used for prediction, explanation, exploration

After War: • UK barely had computers, wasn't until after war that general purpose computing was born • UK economy destroyed at end of war § Empire lost § Huge period of retrenchment § Hard to argue for truly staggering costs involved in producing electronic computers § Huge resources went to atomic bomb because they know from US example that it works • Explosion of operations research post-war

• Incredibly large-scale simulation using mechanical device
	○ Monte Carlo now
	○ Bayesian: score is not flat like golf course, but wave of possibilities
		§ Sees what looks like German

Turing: • Turing trying to build general purpose computers same time as Americans ○ Americans could say that computers are important for bomb ○ British had 6 years empty on resume • Turing using Bayesian methods without having knowledge of Bayesian thinking or branding

• Post-WWII, everyone thought physicists won war
	○ Couldn't hide atom bomb they invented
	○ Got all credibility & funding
	○ Physics of bomb are not hard
	○ Actually building a device is difficult --> chemical engineers at Los Alamos similarly classified 
	○ Took 50 years for world to figure out how data scientists won the war
• Role of Bell Labs as computational, statistical analysis of personal data
	○ For sake of private enterprise
	○ How much of Bell Labs overlaps with what become the NSA? How much of the NSA overlaps with Bletchley Park?
	○ Bell Labs as conspirator with NSA
	
• Statisticians' fallacy: 
	○ Island example: if you test positive for sick, 99% chance you're sick --> wrong
	○ Yet by using Bayesian probabilities, only 50% chance you're sick because given prior probability
	
• Using Bayes = using probability in Wiggins' mind
• In a position where you need to make concrete decisions about which hypotheses you want to test --> because huge amount of labor required


5) Fisher: whole knowledge is in false positive rate (alpha)
	○ False positive rate is 1%
	○ One case in which Fisher's approach works: false positive rate is small, false negative rate is small, and even odds

• Frequentist: uses significance test as grounds for him concluding 
• Bayes - subjectivist 
	○ Ban weight of evidence 
	○ Probabilities being about beliefs

Computer • All-purpose for any numerical calculation- calculator ○ E.g. ENIAC • All-purpose: ○ Symbolic manipulation ○ Turing machine 1936 • Data storage- computer as information processor • Before war computer meant: person, often a woman • Severe resource constrains on doing very high performance computing ○ Geological, temperature, security considerations in where to put data center • UX - user facing GUI

• Bayes: data storage & numerical calculation