An Introduction to Criticla Thinking with Statistics

1. Thinking in Numbers
An Introduction to Critical Thinking with Statistics.
Edmund J Sutcliffe
edmunds@considrd.consulting

2. Critical Thinking
Critical thinking has seven critical features:
● being inquisitive and curious
● being open-minded to different sides
● being able to think systematically
● being analytical
● being persistent to truth
● being confident about critical thinking itself
● and lastly, being mature
Facione, Peter A.; Facione, Noreen C. (March 1993).
"Profiling critical thinking dispositions".
Assessment Update. 5 (2): 1–4.
doi:10.1002/au.3650050202. ISSN 1041-6099

3. Thinking in Numbers
A Statistical Approach
● Data collection
● Descriptive statistics
● Exploratory data analysis
● Estimation
● Hypothesis testing
Think Stats: Probability and Statistics for Programmers
Downey, Allen B (2014)

4. Data Collection
● Consider the question
● Consider the source (author, date, supporting evidence)
● Consider the bias
● Consider logical fallacies
● Consider the hypothesis

5. Cognitive Biases
How Cognitive Biases Influence How You Think and Act
Cherry, Kendra (February 03, 2020)
● Confirmation Bias
● Availability Heuristic
● Halo Effect
● Attention Bias
● Actor-Observer Bias
● Functional Fixedness
● Anchoring Bias
● Misinformation Effect
● False Consensus Effect
● Optimism Bias
● Dunning-Kruger Effect

6. Trustable information
Most of us look for evidence of trustworthiness — of
● Competence
● Honesty
● Reliability
Onora O'Neill

7. The Question
Do first babies tend to arrive late?
● “My two friends that have given birth recently to their first babies, BOTH
went almost 2 weeks overdue before going into labour or being induced.”
● “My first one came 2 weeks late and now I think the second one is going to
come out two weeks early!!”
● “I don’t think that can be true because my sister was my mother’s first and
she was early, as with many of my cousins.”

8. Trustable information
Most of us look for evidence of trustworthiness — of
● Competence
● Honesty
● Reliability
Onora O'Neill
FAIL
Small number of observations
Selection bias
Confirmation bias
Inaccuracy

9. The Question
What do we mean by late ?
What is the length of human gestation ?

10. Consider the question
“What is the length of human gestation ?”
● The average length of human gestation is 280 days, or 40 weeks, from the first day of the
woman's last menstrual period. The medical term for the due date is estimated date of
confinement (EDC) Google's Featured Snippet from Victoria Govenment
● Birth normally occurs at a gestational age of about 40 weeks, though it is common for births to
occur from 37 to 42 weeks Wikipedia Article on Human Gestation
● The length of pregnancy can vary naturally by as much as five weeks, research suggests….
Due dates can be calculated from working out 280 days after the start of the woman's last
menstrual period BBC News Article

11. Consider the source
“What is the length of human gestation ?”
● Google's Featured Snippet from Victoria Govenment last edit August 2014 no mention source
● Wikipedia Article on Human Gestation last edit 30 January 2020 reporting American College of
Obstetricians and Gynecologists - How Your Baby Grows During Pregnancy FAQ answer no
mentioned source
● BBC News Article 7th August 2013 Study of 125 women reporting the journal of Human
Reproduction article produced by US National Institute of Environmental Health Sciences

12. Consider the source
“What is the length of human gestation ?”
● Google's Featured Snippet from Victoria Govenment last edit August 2014 no mention source
● Wikipedia Article on Human Gestation last edit 30 January 2020 reporting American College of
Obstetricians and Gynecologists - How Your Baby Grows During Pregnancy FAQ answer no
mentioned source
● BBC News Article 7th August 2013 Study of 125 women reporting the journal of Human
Reproduction article produced by US National Institute of Environmental Health Sciences
Looks like 40 weeks (280 days)

13. The Question
Do first babies tend to arrive late?
● Gestation period against number of births
Vital Statistics Annual Report 2014, Births

14. The Question
Do first babies tend to arrive late?
● Gestation period against number of births
Vital Statistics Annual Report 2014, Births
FAIL No differentiation of
number of births

15. Can we find the Data
Live births by gestation by child number ?
● Where can we find appropriate data ?
● CDC National Survey of Family Growth
● https://github.com/datasets
● https://datahub.io/
● https://data.europa.eu/
● https://data.gov.ie/
● https://registry.opendata.aws
● https://cloud.google.com/public-datasets
● https://azure.microsoft.com/services/open-datasets/
● https://www.globalfinancialdata.com/

16. National Survey of Family Growth
● Cross-sectional
● Longitudinal
● Sample based
● Over sampled for some population members
● Interview based

17. What does the data look like ?
70623516531616165 1 4000006 50 1 115 11 16255 5211131 2 135 125 055 05 0 0 000
0 55 0
221554 81 1 6 117 1 7 5 1 8 1 7 11 8
0
00 55555 55555
5 555 1 5 5 0 5 5 55 95 5
134551346513475134851349513505135151352513535135451355513565135751358513595136051361513625136351364513655136
6513675136851369513705137151372513735137451375513765137751378513795138051381513825138351384513855138651387513885138
9513905
55555550 55 5 1 0
5 6 7 6 75 75551 11 3 3
15 5 5555515555 5 51323355 3 5 2 5 315 1 211
1 995 515 42 725 27 1254 51 121 11311362155 5 1 0 0 05555 521 0 1111115 55 5 5 55
5555 1 2555555555555555 3 1 3 8 5 55555555165610 62222031200 21 3
200000000000000000000002 0 0 0
000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
22 0 0 0 1 2 2
0000000000000000000000000000000000000000000000000000000000000005622 2295 408888882
000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000 0000000000000000001 3000 20
00000000000000012360000113 820003631.827871901753322139013781345133313211712015 35.04
2015-17 Female Pregnacy Data Set

18. How do we interpret the data ?
dictionary {
*****************************************************************
* NATIONAL SURVEY OF FAMILY GROWTH (NSFG), 2015-2017
* STATA Pregnancy Data Dictionary
*
* Warning: Edit this file at your own risk
*
*****************************************************************
_lines(1)
_column(1) long CASEID %5f "Case identification number"
_column(6) byte PREGORDR %2f "Pregnancy order (number)"
_column(8) byte HOWPREG_N %2f "BB-2 # of Weeks or Months Currently Pregnant"
_column(10) byte HOWPREG_P %1f "BB-2 Current pregnancy length reported in months
or weeks"
_column(11) byte MOSCURRP %1f "Number of Months Currently Pregnant"
_column(12) byte NOWPRGDK %1f "BB-3 Which Trimester -- Current Pregnancy"
_column(13) byte PREGEND1 %1f "BC-1 How Pregnancy Ended - 1st mention"
_column(14) byte PREGEND2 %1f "BC-1 How Pregnancy Ended - 2nd mention"
....
2015-17 Female Pregnacy Data Set Stata Dictionary

19. Choosing the Tool
● Python
○ Google's Colab python notebook platform
○ write your own
● R
● Stata/SPSS/SAS/Minitab

20. Are first babies more likely to be late
Sep 9, 2019
Allen Downey

21. Reporting the Results
● John Kreb's On Crisis
○ Consensus - What we might know
○ Uncertainty - What we don’t know
○ Confidence - What are we doing
○ Self-efficacy - What might the individual do
○ Flexibility - Things will change