+ All Categories
Home > Education > Статистика для журналистов

Статистика для журналистов

Date post: 02-Nov-2014
Category:
Upload: nataly-nikitina
View: 790 times
Download: 1 times
Share this document with a friend
Description:
 
Popular Tags:
35
Being Smart with Statistics Tom Coupé KSE and KEI
Transcript
Page 1: Статистика для журналистов

Being Smart with StatisticsTom Coupé

KSE and KEI

Page 2: Статистика для журналистов

Structure of My Presentation

• Is a change really a change? Is a difference really a difference?

– The Margin of Error

• The Chicken or the Egg?

– Causality versus Correlation

Page 3: Статистика для журналистов

Assignment 1

• What percentage of this class believes that the GDP of their country will double by 2021?

Page 4: Статистика для журналистов

Population Statistic versus Sample Estimate

• Population – the group in which I am interested

• Sample – a subgroup of the population

Page 5: Статистика для журналистов

Why Important?

• Sample Statistic =/= Population Statistic

• Different Samples, Different Sample Statistic

• The ‘variance’ of these estimates uncertainty

illustration.pdf

• Differences can be no differences

• Changes can be no changes

Page 6: Статистика для журналистов

The ICPS Example

• gfk_icps_rel_February_66_eng.pdf

Page 7: Статистика для журналистов

The Margin of Error: 3.2%

• in population: p =0.5

• yes =1, no= 0

• ask one person: our expected ‘answer’ =p

• (p percent says 1, 1-p percent says 0) = p*1+(1-p)*0

• ask many times one person: sometimes 1, sometimes 0

• Variation: p*(1-p)

• Standard Deviation: √variation

• If we ask n individuals (in the ICPS case, 1000)

• Standard deviation divided by √ 1000.

• The margin or error is twice that number

• 2*sqrt(0.5*0.5/1000)=0.032

Page 8: Статистика для журналистов

Meaning of 3.2%

• Population Statistic is likely to be between

• Sample Estimate -3.2%

• and

• Sample Estimate +3.2% Implication for ICPS index

Page 9: Статистика для журналистов

Implications for ICPS index I

• – ‘In January 2011, the Consumer Confidence Index (CCI) in Ukraine fell 7.2pp to 75.’

• or• ‘In January 2011, the Consumer Confidence Index

(CCI) in OUR SAMPLE of UKRAINIANS was 75.’

Page 10: Статистика для журналистов

Implications for ICPS index II

• – ‘In January 2011, the Consumer Confidence Index (CCI) in Ukraine fell 7.2pp .’

• Based on Sample, yes!

• But what about the CCI based on the whole Ukrainian population of consumers?

• “Only expectations of changes in unemployment (IECU) improved marginally, losing 1.6pp to end at 127.4.”

Page 11: Статистика для журналистов

Other Examples – Doing Business

• Changes in the Doing Business Index of the World Bank

• Doing Business in Ukraine - World Bank Group.htm

Page 12: Статистика для журналистов

12

EBA Investment Attractiveness Index

2.56 2.57

3.083.25 3.20 3.28 3.40

2.64

2.222.22

3.14

0

1

2

3

4

5

III/2008 IV/2008 I/2009 II/2009 III/2009 IV/2009 I/2010 II/2010 III/2010 IV/2010 I/2011

EBA Investment Attractiveness Index

Page 14: Статистика для журналистов

Practical Implications

• Point 1 – one ‘true’ number, many estimates

• Point 2 – estimates differ from one sample to another

• Point 3 – changes over time and differences between groups can be due just to changes in sample rather than changes in the underlying true value

Page 15: Статистика для журналистов

Practical Implications

•The world is not simple – don’t fool your readers in believing it is•When reporting numbers, think rather than blindly accept the number you are given•a journalist who is aware of the margin of error, will not be ‘fooled’ into report big conclusions on small differences or small changes

Page 16: Статистика для журналистов

Biased Estimators

• Bias:illustration.pdf

• Not all Samples are “ Good Samples”

– Big Samples

– Random samples!

• Not All Questions are Good Questions

Page 17: Статистика для журналистов

Big Samples

• How do Belgians look like?

• ‘case studies’

Page 18: Статистика для журналистов

Non-Random Samples - Selection

• Selection by Researcher (reporter)– ‘In Search of Excellence: Lessons from America’s

Best-Run Companies’• Self-Selection of Respondents

Page 19: Статистика для журналистов

Problematic Questions

• Leading Questions• Biased Answers

Page 20: Статистика для журналистов

Implication

• When reading numbers, always think about sources of bias!

Page 21: Статистика для журналистов

Causality vs Correlation

Page 22: Статистика для журналистов

Assignment II

• Flip a Coin!

Page 23: Статистика для журналистов

Possible Explanations for Correlation

Page 24: Статистика для журналистов

The Simpsons

(Season 7, "Much Apu About Nothing“)8d840544251f-1333453.vk.flv

Homer: Not a bear in sight. The "Bear Patrol" is working like a charm!

Lisa: That's specious reasoning, Dad.

Homer: [uncomprehendingly] Thanks, honey.

Lisa: By your logic, I could claim that this rock keeps tigers away.

Homer: Hmm. How does it work? Lisa: It doesn't work; it's just a

stupid rock! Homer: Uh-huh. Lisa: But I don't see any tigers

around, do you? Homer: (pause) Lisa, I want to buy

your rock.

Page 25: Статистика для журналистов

Causality versus correlation

• Bain:

‘our clients outperform the market 3 to 1’

Page 26: Статистика для журналистов

ICPS

• “The main reason for growing pessimism among consumers in January 2011 is increased inflationary pressure and the resulting inflationary expectations, as prices for most product groups and consumer services rose: food, fuel and residential services and utilities all showed marked increases,” says ICPS Deputy Director Maksym Boroda. “At the same time, unpromising economic expectations have been spurred by a noticeable financial pinch among ordinary Ukrainians, after having spent considerable amounts during the holiday season. This can be seen in the dynamic of the various components of the CCI, where estimates of current financial standing and the inclination to make major household purchases declined the most”

Page 27: Статистика для журналистов

Happiness

• Two percent of Ukrainians unhappier over year of Yanukovych's presidency, according to poll.htm

• http://www.interfax.com.ua/ukr/press-conference/63304/

Page 28: Статистика для журналистов

How to Prove Causality?

• Controlled Experiment!

Page 29: Статистика для журналистов

Practical Implications for Journalists

• The world is not simple – don’t fool your readers in believing it is

• When reporting, think about causality rather than correlation – don’t confuse these two!

• Be critical about any causality claim – it is very hard to establish causality so as an interviewer you really can ask tough questions about proof of claims.

Page 30: Статистика для журналистов
Page 31: Статистика для журналистов

Misleading with statistics

• Graphs• Choice of Statistic• Per Capita?• Real versus nominal

Page 32: Статистика для журналистов

Sources of Interesting Statistics - International

• World bank data archive

– http://data.worldbank.org/

• European Social Survey (includes Ukraine)

– http://www.europeansocialsurvey.org/index.php

• World Value Survey (includes Belarus and Ukraine)

– http://www.worldvaluessurvey.org/

• EBRD Surveys (includes Belarus and Ukraine)

– LITS http://www.ebrd.com/pages/research/analysis/publications/transition.shtml

– BEEPS http://www.ebrd.com/pages/research/analysis/surveys/beeps.shtml

• TiMMS – PISA – PIRLS (includes Ukraine)

– http://timss.bc.edu/

– http://www.pisa.oecd.org/pages/0,2987,en_32252351_32235731_1_1_1_1_1,00.html

• GOOGLE!!!

Page 33: Статистика для журналистов

Sources of Interesting Statistics - Belarus

• The think tanks

– http://research.by

• IFC Business Environment Surveys

– http://belarus.bel.biz/?p=632

Page 34: Статистика для журналистов

Sources of Interesting Statistics - Ukraine

• Kyiv Institute for International Sociology

– http://kiis.com.ua/ua/bank

• IFC surveys on Business climate

– http://www.ifc.org/ifcext/uspp.nsf/Content/PMSurveysRU

• Ukrainian Longitudinal Monitoring Survey

– http://www.iza.org/de/webcontent/research/ra5

• The think tanks

– www.ier.com.ua

– http://www.icps.com.ua/

– www.uceps.org

– www.case-ukraine.com.ua

Page 35: Статистика для журналистов

Recommended