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‘Social Sharing’ By Means of Distributed Computing: Some

Results From A Study of SETI@home

Hans-Jürgen EngelbrechtMassey University

August 2005

H.Engelbrecht@massey.ac.nzhttp://www.massey.ac.nz/~hengelbr/

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1. Introduction

Information and Communication Technologies (ICT) are General Purpose Technologies.

One of many associated innovations: Distributed computing, grid computing.

Enables non-commercial sharing of physical, rivalrous goods via the Internet: Such ‘social sharing’ is a form of economic production (Benkler, 2004).

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‘Shareable goods’

Sharing of computing power and bandwidth.

Two features of ‘shareable goods’ (Benkler, 2004): They are lumpy (PCs come in discrete units). They are of ‘mid-grained’ granularity (PCs are

widely privately owned and systematically have slack capacity).

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‘Shareable goods’ ctd.

What determines the extent of ‘social sharing’?

Technological conditions, but also cultural practices and tastes (Benkler, 2004) and social and legal conditions (David, 2004).

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2. SETI@home

Prime example of a voluntary non-commercial Internet-based distributed computing project: SETI@home.

Launched in May 1999.Download screen saver.Analysis of Arecibo radio telescope data.SETI@home the most powerful special

purpose supercomputer in the world.

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SETI@home ctd.

Worldwide phenomenon (except for Mauritius, Palestine and Vatican City).

Incentives build into client interface, e.g. user and results data.

By Dec. 2004, there had been: More than 5 million contributors. Providing over 2 million years of CPU time

(more than 1000 years of CPU time during the last day alone).

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SETI@home ctd.

SETI country data available for: Dec. 10th, 2002; Dec. 11th, 2003; Dec. 13th, 2004.

Dependent variables used in the regression model:SETI participants per capita.SETI results per capita (measures actual

outcomes and is arguably a better Internet-intensity variable than ‘hours of use’).

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3. Explanatory variables What determines SETI@home cross-country

participation and its intensity? Aim: To include as many countries as possible. Therefore, modelling is severely restricted and I

use only a few key explanatory variables in the regressions: ITU’s ‘Digital Access Index’ (DAI). GDP per capita (gdp). The ‘Human Development Index’ (HDI). Country group dummy variables.

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The Digital Access Index (DAI) ITU: The DAI tries to measure “the overall ability

of individuals in a country to access and use ICTs…”. It provides the first truly global ICT ranking.

The DAI is a composite index made up of 8 underlying indicators to capture: infrastructure (fixed telephone & mobile telephone

subscribers), affordability (Internet access price), ‘knowledge’ (adult literacy, school enrolment), quality (broadband subscribers, international

Internet bandwidth), actual usage of ICTs (Internet users).

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Components of the Digital Access Index (DAI), 2002:

Indicator Goal-post

Sub-Components (in italics) and their composition

Fixed telephone subscribers per 100 inhabitants1

60

Mobile subscribers per 100 inhabitants

100

Each has a one half weight for infrastructure, which proxies overall ICT network development.

Adult literacy2 100 Overall school enrolment (primary, secondary and tertiary)2

100 Literacy has a two-third weight and enrolment a one-third weight for knowledge, which affects a country’s ability to use new technologies.

Internet access price (20 hours per month) as percent of monthly per capita income3

1 This is subtracted from 1 to form an indicator that proxies affordability of Internet access. (1=free Internet)

Broadband subscribers per 100 inhabitants4

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Intern. Internet bandwidth per capita 10’000

Each has a one half weight for quality of access to ICTs.

Internet users per 100 inhabitants 85 This indicator proxies Internet usage.

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The DAI ctd.

Hypothesis:

The DAI is a positive and statistically significant determinant of SETI@home participation and its intensity. This would mean: On average, SETI@home

participation and its intensity across countries matches inter-country differences in ICT accessibility.

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Other explanatory variables

GDP per capita (in PPP adjusted US $): Traditional proxy for ‘standard of living’. Key

explanatory variable in numerous ICT and Internet diffusion studies.

It is expected to be a positive and statistically significant determinant of SETI@home participation and its intensity.

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Other explanatory variables ctd.

The HDI: A composite index which has emerged as the

preferred measure of ‘development’. It measures important dimensions of human

development neglected by gdp, such as: living a long and health life and being educated.

It is best included alongside DAI and gdp as an additional explanatory variable.

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Other explanatory variables ctd.

Country group dummy variables: ITU’s “developed & advanced countries” versus

‘the rest’. Alternatively: 6 regional dummy variables

(similar to Caselli and Coleman II, 2001).

See “Appendix: Country List”.

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4. Regression analysis

Matching data for 172 countries.Dependent variables alternatively in 2004

levels and 2002-2004 changes. Most regressions estimated in double-log

form.OLS with White’s heteroscedasticity

correction.Box-Cox regressions.

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Regression results (1) (2) (3) (4) Dependent Variable: Indep. Variables:

Results per capita 2004

Participants per capita

2004

Change in results per capita,

2002-04

Change in participants per capita, 2002-04

DAI 2002 0.945b

(2.25) 1.065a

(3.54) 0.745b

(2.17) 0.892a

(3.02) gdp 2002 1.144a

(4.82) 1.031a

(5.36) 0.938a

(4.96) 0.985a

(5.43) Dev&adv dummy

1.121a

(3.52) 0.769a

(3.09) 1.013a

(2.98) 0.689a

(2.91) Intercept -4.383a

(-5.59) -9.348a

(-15.86) -4.457a

(-6.94) -10.668a

(-18.65) Adj. R2 0.70 0.77 0.69 0.73 DW 1.76 1.57 1.73 1.73 JB 1.28 1.08 5.68 0.32

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Regression results ctd.Increasing DAI and gdp by 1% increases

dependent variables by a similar %tage (elasticity of ‘change in results per capita’ with respect to DAI somewhat lower).

DAI, gdp, and the general divide between rich&poor countries can explain most of the cross-country variation in SETI@home participation and its intensity (see R2s).

HDI dropped from preferred regressions (DAI and HDI highly correlated).

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5. The global SETI@home digital divide

By Dec. 2004, developed & advanced countries (about 15% of the sample population) accounted for over 90% of submitted results.

But: Indications of a slowly narrowing global SETI@home digital divide! Growth rates for ‘users’ and ‘results’ higher in

”the rest”.

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Developed & advanced countries versus ‘the rest’:

December 2004 totals

Dev. & adv. countries:

The rest: % the rest:

No. of total users: 4,511,609 604,821 11.8% No. of total results: 1,507,659,459 164,968,938 9.9% Total population: 900,395,111 4,975,626,881 84.7% December 2002 totals

Dev. & adv. countries:

The rest: % the rest:

No. of total users: 3,559,136 425,122 10.7% No. of total results: 661,872,079 47,186,802 6.7% Total population: 899,335,782 4,975,979,881 84.7%

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Developed & advanced countries versus ‘the rest’ ctd.:

Percentage increase (Dec. 2002 - Dec. 2004): Dev. & adv.

countries The rest:

No. of total users:

26.8% 42.3%

No. of results:

127.8% 249.6%

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Developed & advanced countries versus ‘the rest’ ctd.:

Per capita and per user results: Dev. & adv.

countries: The rest: The rest as % of

dev. & adv. cont.: No. of total users per capita by Dec. 2004:

0.00501

0.00012

2.43%

No. of total users per capita by Dec. 2002:

0.00396

0.000085

2.16%

No. of total results per capita by Dec. 2004:

1.67444

0.03316

1.98%

No. of total results per capita by Dec. 2002:

0.73596

0.00948

1.29%

No. of total results per user by Dec. 2004:

334.17

272.76

81.6%

No. of total results per user by Dec. 2002:

185.96

111

59.7%

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6. Concluding comments

Further research needed: For a less heterogeneous group of countries. This

would allow more sophisticated modelling. More sophisticated models are needed to enable more

specific policy conclusions. Will non-commercial ‘social sharing’ via the

Internet become a dominant mode of economic production? There is huge potential for it, but commercial distributed

computing might greatly affect its realization.