Session 2 of my data analysis course at BME.

1. session#2 Divényi János @divenyi.janos

3. b.socrative.com
Student login
into room BMEADAT

4. How to find answers
to relevant questions
using data

6. QUESTION
DATA
ANALYSIS
PRESENTATION

7. QUESTION

8. QUESTION
DATA

9. GET DATA

12. https://www.quora.com/Where-can-I-find-large-datasets-open-to-the-public
https://sqlbelle.com/2015/01/16/data-sets-for-bianalyticsvisualization-projects

13. https://www.quora.com/Where-can-I-find-large-datasets-open-to-the-public
https://sqlbelle.com/2015/01/16/data-sets-for-bianalyticsvisualization-projects

14. MEASURE
WHAT YOU WANT

18. http://boredbug.com/wp-content/uploads/2015/08/onesecondbeforedisaster.jpg

19. http://www.webpages.uidaho.edu/ed571/571-Modules/M3/Sampling_Design-Funny.gif

20. Prezi & Conversion Rate

21. Street Bump, Boston

24. How does
a new piece of
information
affects
what we know
about the world?
www.bigstockphoto.com

26. Down syndrome screening

27. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047

28. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047
Down if positive?

33. Down if positive?

34. Down if positive?

35. Down if positive?
P(+, Down) / (P(+, Down) + P(+, not Down))

36. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047
P(+, Down) / (P(+, Down) + P(+, not Down))

37. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047
0.83*0.0025 / (0.83*0.0025 + 0.047*0.9975)
P(+, Down) / (P(+, Down) + P(+, not Down))

38. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047
Down if positive 0.0424
0.83*0.0025 / (0.83*0.0025 + 0.047*0.9975)
P(+, Down) / (P(+, Down) + P(+, not Down))

39. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047
Down if positive 0.0424
0.83*0.0025 / (0.83*0.0025 + 0.047*0.9975)
P(+, Down) / (P(+, Down) + P(+, not Down))

40. Unconditional risk 1:400 = 0.0025
Discovery rate 0.83
False positive rate 0.047
Down if positive 0.0424
0.83*0.0025 / (0.83*0.0025 + 0.047*0.9975)
P(+, Down) / (P(+, Down) + P(+, not Down))

42. Bayes’ Theorem
P(B|A) =
P(A|B) · P(B)
P(A)
P(B|A) =
P(A|B) · P(B)
P(A|B) · P(B) + P(A|not B) · P(not B)

43. 1% prevalence
99% accurate test
positive result means risk of
Simplistic example

44. 1% prevalence
99% accurate test
positive result means risk of
50%
Simplistic example

45. In 1999 Sally Clark was accused for murdering her
2 children after she sequentially claimed that
they died in sudden infant death syndrome (SIDS).
The probability of SIDS is 1 in 8500.

46. In 1999 Sally Clark was accused for murdering her
2 children after she sequentially claimed that
they died in sudden infant death syndrome (SIDS).
The probability of SIDS is 1 in 8500.
1. If you were the judge
what other probability
you would want to know?
2. Would you convict her?

47. In 1999 Sally Clark was accused for murdering her
2 children after she sequentially claimed that
they died in sudden infant death syndrome (SIDS).
The probability of SIDS is 1 in 8500.
1. If you were the judge
what other probability
you would want to know?
2. Would you convict her?
3. Do you think she was convicted?

48. b.socrative.com
Student login
into room BMEADAT