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Beyond Big Data | Matthew Salganik | TEDxPrincetonU


I’d like to talk to you today about Big

I’d like to talk to you today about Big Data

Data

Data it’s a term we’ve probably all heard a

it’s a term we’ve probably all heard a

it’s a term we’ve probably all heard a lot recently one of the things that’s

lot recently one of the things that’s

lot recently one of the things that’s really interesting about it though is

really interesting about it though is

really interesting about it though is that it seems to mean very different

that it seems to mean very different

that it seems to mean very different things to different people some people

things to different people some people

things to different people some people when they hear the term Big Data they

when they hear the term Big Data they

when they hear the term Big Data they think of money they think about how it

think of money they think about how it

think of money they think about how it can be used by companies to design

can be used by companies to design

can be used by companies to design products more efficiently and market

products more efficiently and market

products more efficiently and market them more effectively other people when

them more effectively other people when

them more effectively other people when they hear the term Big Data they think

they hear the term Big Data they think

they hear the term Big Data they think about saving the world they think about

about saving the world they think about

about saving the world they think about how governments and NGOs can use this

how governments and NGOs can use this

how governments and NGOs can use this new kind of information to help solve

new kind of information to help solve

new kind of information to help solve important social problems some other

important social problems some other

important social problems some other people though when they hear the term

people though when they hear the term

people though when they hear the term Big Data they think of surveillance they

Big Data they think of surveillance they

Big Data they think of surveillance they think about all the enormous amounts of

think about all the enormous amounts of

think about all the enormous amounts of potentially very sensitive information

potentially very sensitive information

potentially very sensitive information that’s being collected about all of us

that’s being collected about all of us

that’s being collected about all of us all the time but for me when I think

all the time but for me when I think

all the time but for me when I think about big data I think about something

about big data I think about something

about big data I think about something different I think about a urinal so this

different I think about a urinal so this

different I think about a urinal so this though as you all recognize is not just

though as you all recognize is not just

though as you all recognize is not just any urinal this is a very very special

any urinal this is a very very special

any urinal this is a very very special urinal this is fountain by Duchamp this

urinal this is fountain by Duchamp this

urinal this is fountain by Duchamp this is one of my favorite pieces of art and

is one of my favorite pieces of art and

is one of my favorite pieces of art and what I love about this is the way that

what I love about this is the way that

what I love about this is the way that Duchamp took something that was created

Duchamp took something that was created

Duchamp took something that was created for one purpose and then repurposed it

for one purpose and then repurposed it

for one purpose and then repurposed it for something else and it turns out that

for something else and it turns out that

for something else and it turns out that this idea of repurposing is central to

this idea of repurposing is central to

this idea of repurposing is central to the way that scientists learn from big

the way that scientists learn from big

the way that scientists learn from big data because most of the big data

data because most of the big data

data because most of the big data sources that exist were created by

sources that exist were created by

sources that exist were created by companies and governments for reasons

companies and governments for reasons

companies and governments for reasons other than doing research and so

other than doing research and so

other than doing research and so scientists have to take data that was

scientists have to take data that was

scientists have to take data that was created for one purpose and like Duchamp

created for one purpose and like Duchamp

created for one purpose and like Duchamp repurpose it for something else and this

repurpose it for something else and this

repurpose it for something else and this is actually really different than the

is actually really different than the

is actually really different than the way social scientists have gone about

way social scientists have gone about

way social scientists have gone about learning about the world in the past and

learning about the world in the past and

learning about the world in the past and if I had to pick one piece of art that

if I had to pick one piece of art that

if I had to pick one piece of art that could illustrate this sort of more

could illustrate this sort of more

could illustrate this sort of more traditional style of social science

traditional style of social science

traditional style of social science research it would be David so when

research it would be David so when

research it would be David so when Michelangelo wanted to create David he

Michelangelo wanted to create David he

Michelangelo wanted to create David he didn’t look around for a piece of stone

didn’t look around for a piece of stone

didn’t look around for a piece of stone that kind of sort of looked like David

that kind of sort of looked like David

that kind of sort of looked like David he spent three years working to create

he spent three years working to create

he spent three years working to create David and so this illustrates really the

David and so this illustrates really the

David and so this illustrates really the two styles of research that we see right

two styles of research that we see right

two styles of research that we see right now there is a ready-made style where

now there is a ready-made style where

now there is a ready-made style where researchers Duchamp like take data that

researchers Duchamp like take data that

researchers Duchamp like take data that was created let’s say by Twitter or

was created let’s say by Twitter or

was created let’s say by Twitter or Facebook and repurpose it for research

Facebook and repurpose it for research

Facebook and repurpose it for research and then there’s the other style where

and then there’s the other style where

and then there’s the other style where researchers create their own data using

researchers create their own data using

researchers create their own data using like surveys or experiments but

like surveys or experiments but

like surveys or experiments but increasingly what we’re going to see is

increasingly what we’re going to see is

increasingly what we’re going to see is that there are limits to both of these

that there are limits to both of these

that there are limits to both of these pure approaches the Duchamp’s will

pure approaches the Duchamp’s will

pure approaches the Duchamp’s will discover that there are things that you

discover that there are things that you

discover that there are things that you can’t learn just by repurposing data and

can’t learn just by repurposing data and

can’t learn just by repurposing data and the michelangelo’s will increasingly

the michelangelo’s will increasingly

the michelangelo’s will increasingly feel like they’re being inefficient and

feel like they’re being inefficient and

feel like they’re being inefficient and wasteful by not taking advantage of all

wasteful by not taking advantage of all

wasteful by not taking advantage of all the ready-made big data that exists so I

the ready-made big data that exists so I

the ready-made big data that exists so I think the future of social research is a

think the future of social research is a

think the future of social research is a hybrid of these two strategies it’s

hybrid of these two strategies it’s

hybrid of these two strategies it’s going to be part ready-made and part

going to be part ready-made and part

going to be part ready-made and part custom-made and that’s going to allow us

custom-made and that’s going to allow us

custom-made and that’s going to allow us to do things that we could never do

to do things that we could never do

to do things that we could never do before with either of these pure

before with either of these pure

before with either of these pure strategies so let me give you an example

strategies so let me give you an example

strategies so let me give you an example of a beautiful piece of research that

of a beautiful piece of research that

of a beautiful piece of research that illustrates this hybrid strategy this is

illustrates this hybrid strategy this is

illustrates this hybrid strategy this is a study that was conducted by Josh

a study that was conducted by Josh

a study that was conducted by Josh blumenstock and colleagues and it was

blumenstock and colleagues and it was

blumenstock and colleagues and it was published in science a few years ago

published in science a few years ago

published in science a few years ago before I tell you about what they did

before I tell you about what they did

before I tell you about what they did let me tell you a little bit about the

let me tell you a little bit about the

let me tell you a little bit about the problem they were trying to solve let’s

problem they were trying to solve let’s

problem they were trying to solve let’s say you want to eliminate poverty in the

say you want to eliminate poverty in the

say you want to eliminate poverty in the world so that’s a goal I think many of

world so that’s a goal I think many of

world so that’s a goal I think many of us would share but one of the many many

us would share but one of the many many

us would share but one of the many many many problems you would encounter on the

many problems you would encounter on the

many problems you would encounter on the way to that goal is that it’s actually

way to that goal is that it’s actually

way to that goal is that it’s actually hard to know where poverty is and how

hard to know where poverty is and how

hard to know where poverty is and how poverty is changing over time then this

poverty is changing over time then this

poverty is changing over time then this may be kind of a surprising thing for

may be kind of a surprising thing for

may be kind of a surprising thing for people in wealthy countries because we

people in wealthy countries because we

people in wealthy countries because we happen to live in countries where for

happen to live in countries where for

happen to live in countries where for example in the US the National

example in the US the National

example in the US the National Statistical system collects reliable and

Statistical system collects reliable and

Statistical system collects reliable and accurate information about our society

accurate information about our society

accurate information about our society but in many of the world’s poorest

but in many of the world’s poorest

but in many of the world’s poorest countries where this information is most

countries where this information is most

countries where this information is most needed it’s not collected and so this is

needed it’s not collected and so this is

needed it’s not collected and so this is a challenge for policymakers because

a challenge for policymakers because

a challenge for policymakers because they’re essentially trying to operate in

they’re essentially trying to operate in

they’re essentially trying to operate in the dark they they can’t know where the

the dark they they can’t know where the

the dark they they can’t know where the problem is which makes it hard to target

problem is which makes it hard to target

problem is which makes it hard to target the resources effectively and it’s hard

the resources effectively and it’s hard

the resources effectively and it’s hard to see how well they’re doing because

to see how well they’re doing because

to see how well they’re doing because they can’t measure the outcomes and so

they can’t measure the outcomes and so

they can’t measure the outcomes and so many many people have worked on the

many many people have worked on the

many many people have worked on the problem of improving measurement of

problem of improving measurement of

problem of improving measurement of poverty but Josh blumenstock and

poverty but Josh blumenstock and

poverty but Josh blumenstock and colleagues took a different approach so

colleagues took a different approach so

colleagues took a different approach so what they did is they started with the

what they did is they started with the

what they did is they started with the call records from the largest mobile

call records from the largest mobile

call records from the largest mobile phone provider in Rwanda so this was 1.5

phone provider in Rwanda so this was 1.5

phone provider in Rwanda so this was 1.5 million customers and they have very

million customers and they have very

million customers and they have very detailed records about the patterns of

detailed records about the patterns of

detailed records about the patterns of calling and texting for all of these

calling and texting for all of these

calling and texting for all of these people but these ready-made call records

people but these ready-made call records

people but these ready-made call records do not have the thing that the research

do not have the thing that the research

do not have the thing that the research actually cared about which is a measure

actually cared about which is a measure

actually cared about which is a measure of poverty and so what they did is they

of poverty and so what they did is they

of poverty and so what they did is they took us

took us

took us sample a random sample from these set of

sample a random sample from these set of

sample a random sample from these set of call records they phoned the people up

call records they phoned the people up

call records they phoned the people up and they gave them a traditional social

and they gave them a traditional social

and they gave them a traditional social science survey to measure their poverty

science survey to measure their poverty

science survey to measure their poverty so they have this custom-made data set

so they have this custom-made data set

so they have this custom-made data set and they have this ready-made data set

and they have this ready-made data set

and they have this ready-made data set and then what I love about this study is

and then what I love about this study is

and then what I love about this study is the way that they link them up together

the way that they link them up together

the way that they link them up together so let me walk you through that process

so let me walk you through that process

so let me walk you through that process now so the first thing they did is a

now so the first thing they did is a

now so the first thing they did is a process called feature engineering where

process called feature engineering where

process called feature engineering where they created an enormous matrix where

they created an enormous matrix where

they created an enormous matrix where there’s one row for each person and one

there’s one row for each person and one

there’s one row for each person and one column for each feature and these

column for each feature and these

column for each feature and these features could be things like number of

features could be things like number of

features could be things like number of outgoing calls number of incoming calls

outgoing calls number of incoming calls

outgoing calls number of incoming calls but they could also be much more subtle

but they could also be much more subtle

but they could also be much more subtle so for example of the people that you’ve

so for example of the people that you’ve

so for example of the people that you’ve called what’s the probability if they

called what’s the probability if they

called what’s the probability if they called each other so they build many

called each other so they build many

called each other so they build many many complicated features like this and

many complicated features like this and

many complicated features like this and then they train a machine learning model

then they train a machine learning model

then they train a machine learning model to use those features to predict what

to use those features to predict what

to use those features to predict what people said on the survey so for example

people said on the survey so for example

people said on the survey so for example this machine learning model might

this machine learning model might

this machine learning model might discover that people who make more

discover that people who make more

discover that people who make more international calls tend to be more

international calls tend to be more

international calls tend to be more wealthy as an example of the kind of

wealthy as an example of the kind of

wealthy as an example of the kind of thing it might find it actually finds

thing it might find it actually finds

thing it might find it actually finds many more subtle patterns so once you

many more subtle patterns so once you

many more subtle patterns so once you have this machine learning model then

have this machine learning model then

have this machine learning model then you can impute the survey responses for

you can impute the survey responses for

you can impute the survey responses for all 1.49 nine million other people so

all 1.49 nine million other people so

all 1.49 nine million other people so impute is just a fancy social science

impute is just a fancy social science

impute is just a fancy social science term for guessing and so in essence what

term for guessing and so in essence what

term for guessing and so in essence what they’ve done here is by doing a survey

they’ve done here is by doing a survey

they’ve done here is by doing a survey of a thousand people they’ve been able

of a thousand people they’ve been able

of a thousand people they’ve been able to approximate what would happen if you

to approximate what would happen if you

to approximate what would happen if you did a survey of 1.5 million people then

did a survey of 1.5 million people then

did a survey of 1.5 million people then what they did is they estimated where

what they did is they estimated where

what they did is they estimated where everyone lived even though the call

everyone lived even though the call

everyone lived even though the call records did not have people’s names and

records did not have people’s names and

records did not have people’s names and addresses it turns out that what towers

addresses it turns out that what towers

addresses it turns out that what towers you make phone calls from at night is a

you make phone calls from at night is a

you make phone calls from at night is a pretty good approximation of where you

pretty good approximation of where you

pretty good approximation of where you live so here you see how they were able

live so here you see how they were able

live so here you see how they were able to connect up this ready-made call data

to connect up this ready-made call data

to connect up this ready-made call data with this custom-made survey data and

with this custom-made survey data and

with this custom-made survey data and now they’re able to produce high

now they’re able to produce high

now they’re able to produce high resolution Geographic estimates of

resolution Geographic estimates of

resolution Geographic estimates of poverty in Rwanda and here’s what those

poverty in Rwanda and here’s what those

poverty in Rwanda and here’s what those look like so this is a partial map of

look like so this is a partial map of

look like so this is a partial map of Rwanda I want to call attention to the

Rwanda I want to call attention to the

Rwanda I want to call attention to the square in the lower right corner so the

square in the lower right corner so the

square in the lower right corner so the scale of that is one kilometer by one

scale of that is one kilometer by one

scale of that is one kilometer by one kilometer and so you can see that they

kilometer and so you can see that they

kilometer and so you can see that they are able to make estimates for very very

are able to make estimates for very very

are able to make estimates for very very small geographic areas estimates that

small geographic areas estimates that

small geographic areas estimates that would be very helpful to policymakers so

would be very helpful to policymakers so

would be very helpful to policymakers so now you may be

now you may be

now you may be like are these estimates even accurate

like are these estimates even accurate

like are these estimates even accurate that’s the important question and the

that’s the important question and the

that’s the important question and the unfortunate truth is we don’t know

unfortunate truth is we don’t know

unfortunate truth is we don’t know because no one has ever made estimates

because no one has ever made estimates

because no one has ever made estimates this precise before however what you

this precise before however what you

this precise before however what you would really like to do is you would

would really like to do is you would

would really like to do is you would like to be able to compare these

like to be able to compare these

like to be able to compare these measurements somehow to some kind of

measurements somehow to some kind of

measurements somehow to some kind of gold standard measure and it turns out

gold standard measure and it turns out

gold standard measure and it turns out that a few years before their study the

that a few years before their study the

that a few years before their study the Rwandan government conducted a

Rwandan government conducted a

Rwandan government conducted a demographic and health survey which is a

demographic and health survey which is a

demographic and health survey which is a traditional expensive high-quality

traditional expensive high-quality

traditional expensive high-quality Social Survey that can reasonably be

Social Survey that can reasonably be

Social Survey that can reasonably be considered a gold standard so the

considered a gold standard so the

considered a gold standard so the demographic and health survey was not

demographic and health survey was not

demographic and health survey was not able to produce estimates at this small

able to produce estimates at this small

able to produce estimates at this small of a geographic level but it was able to

of a geographic level but it was able to

of a geographic level but it was able to produce estimates for the Rwanda sturdy

produce estimates for the Rwanda sturdy

produce estimates for the Rwanda sturdy regions and so what blumenstock and

regions and so what blumenstock and

regions and so what blumenstock and colleagues did is they aggregated their

colleagues did is they aggregated their

colleagues did is they aggregated their estimates up to these 30 regions and

estimates up to these 30 regions and

estimates up to these 30 regions and they produced a map like this so on this

they produced a map like this so on this

they produced a map like this so on this map darker colors indicate higher levels

map darker colors indicate higher levels

map darker colors indicate higher levels of poverty and so these are the

of poverty and so these are the

of poverty and so these are the estimates that come from this

estimates that come from this

estimates that come from this combination of the ready-made and

combination of the ready-made and

combination of the ready-made and custom-made data and now you may be

custom-made data and now you may be

custom-made data and now you may be wondering how well does this match the

wondering how well does this match the

wondering how well does this match the gold standard measure and so here’s the

gold standard measure and so here’s the

gold standard measure and so here’s the other estimate from the demographic and

other estimate from the demographic and

other estimate from the demographic and I’ll survive and so you can see in the

I’ll survive and so you can see in the

I’ll survive and so you can see in the paper they actually have a lot of very

paper they actually have a lot of very

paper they actually have a lot of very detailed technical comparisons which I’m

detailed technical comparisons which I’m

detailed technical comparisons which I’m just going to summarize the saying they

just going to summarize the saying they

just going to summarize the saying they match really well so for example you can

match really well so for example you can

match really well so for example you can see in the center of the countries both

see in the center of the countries both

see in the center of the countries both approaches detect the region of high

approaches detect the region of high

approaches detect the region of high poverty and then directly beneath that

poverty and then directly beneath that

poverty and then directly beneath that they have a region of higher levels of

they have a region of higher levels of

they have a region of higher levels of wealth so this is really exciting that

wealth so this is really exciting that

wealth so this is really exciting that this new approach to measurement can

this new approach to measurement can

this new approach to measurement can reproduce this much more traditional

reproduce this much more traditional

reproduce this much more traditional well-established measurement technique

well-established measurement technique

well-established measurement technique but then you might be saying well why

but then you might be saying well why

but then you might be saying well why should we care like if we already have

should we care like if we already have

should we care like if we already have this gold standard technique why should

this gold standard technique why should

this gold standard technique why should we be interested in this new technique

we be interested in this new technique

we be interested in this new technique at all and the answer is that this new

at all and the answer is that this new

at all and the answer is that this new technique is 10 times faster and 50

technique is 10 times faster and 50

technique is 10 times faster and 50 times cheaper so 50 times cheaper that

times cheaper so 50 times cheaper that

times cheaper so 50 times cheaper that is not like 10% cheaper 20% cheaper

is not like 10% cheaper 20% cheaper

is not like 10% cheaper 20% cheaper that’s like 50 times cheaper and so that

that’s like 50 times cheaper and so that

that’s like 50 times cheaper and so that makes a huge huge difference so that

makes a huge huge difference so that

makes a huge huge difference so that enables all kinds of new things so let

enables all kinds of new things so let

enables all kinds of new things so let me just give you one concrete example so

me just give you one concrete example so

me just give you one concrete example so instead of doing the demographic and

instead of doing the demographic and

instead of doing the demographic and health survey every five years as

health survey every five years as

health survey every five years as happens now you could do it every month

happens now you could do it every month

happens now you could do it every month so in wealthy countries we don’t have to

so in wealthy countries we don’t have to

so in wealthy countries we don’t have to wait every five years to get measures of

wait every five years to get measures of

wait every five years to get measures of our society we track things

our society we track things

our society we track things like the unemployment rate every month

like the unemployment rate every month

like the unemployment rate every month and why should it be that people in poor

and why should it be that people in poor

and why should it be that people in poor countries don’t have the same level of

countries don’t have the same level of

countries don’t have the same level of measurement as well so that’s just one

measurement as well so that’s just one

measurement as well so that’s just one example of the kind of thing that we can

example of the kind of thing that we can

example of the kind of thing that we can do when the cost drops by a factor of 50

do when the cost drops by a factor of 50

do when the cost drops by a factor of 50 and scientists will think of lots of

and scientists will think of lots of

and scientists will think of lots of other creative things that can be done

other creative things that can be done

other creative things that can be done as well now the scientist in me also

as well now the scientist in me also

as well now the scientist in me also wants to clarify that this is not a

wants to clarify that this is not a

wants to clarify that this is not a hundred percent of a fair apples to

hundred percent of a fair apples to

hundred percent of a fair apples to apples comparison because there are

apples comparison because there are

apples comparison because there are about 70 years of theoretical results

about 70 years of theoretical results

about 70 years of theoretical results and empirical know-how underlying the

and empirical know-how underlying the

and empirical know-how underlying the custom-made demographic and health

custom-made demographic and health

custom-made demographic and health survey we know a lot about that kind of

survey we know a lot about that kind of

survey we know a lot about that kind of technique and there’s much less of a

technique and there’s much less of a

technique and there’s much less of a theoretical foundation for this new

theoretical foundation for this new

theoretical foundation for this new approach that combines ready-mades and

approach that combines ready-mades and

approach that combines ready-mades and custom aids however learning from big

custom aids however learning from big

custom aids however learning from big data sources and figuring out how we can

data sources and figuring out how we can

data sources and figuring out how we can do it reliably is an incredibly active

do it reliably is an incredibly active

do it reliably is an incredibly active area of research right now and I’m

area of research right now and I’m

area of research right now and I’m really confident that we’re gonna make a

really confident that we’re gonna make a

really confident that we’re gonna make a lot of progress in the coming years so

lot of progress in the coming years so

lot of progress in the coming years so stepping back for a second from this

stepping back for a second from this

stepping back for a second from this study I hope that you can see now some

study I hope that you can see now some

study I hope that you can see now some of the points that we talked about at

of the points that we talked about at

of the points that we talked about at the beginning so this study is an

the beginning so this study is an

the beginning so this study is an example of how companies are potentially

example of how companies are potentially

example of how companies are potentially sitting on lots of valuable information

sitting on lots of valuable information

sitting on lots of valuable information that they are not currently extracting

that they are not currently extracting

that they are not currently extracting from their big data it’s also an example

from their big data it’s also an example

from their big data it’s also an example of how when analyzed appropriately big

of how when analyzed appropriately big

of how when analyzed appropriately big data sources can help address important

data sources can help address important

data sources can help address important social problems and it’s a reminder that

social problems and it’s a reminder that

social problems and it’s a reminder that enormous amounts of data are being

enormous amounts of data are being

enormous amounts of data are being collected about us but what I love about

collected about us but what I love about

collected about us but what I love about this study well I think it’s so great is

this study well I think it’s so great is

this study well I think it’s so great is because it’s a beautiful example of this

because it’s a beautiful example of this

because it’s a beautiful example of this hybrid style that is the ready-made call

hybrid style that is the ready-made call

hybrid style that is the ready-made call data alone was not enough the

data alone was not enough the

data alone was not enough the custom-made survey data was not enough

custom-made survey data was not enough

custom-made survey data was not enough it was only through the combination of

it was only through the combination of

it was only through the combination of these two things that they were able to

these two things that they were able to

these two things that they were able to accomplish this goal and so I hope that

accomplish this goal and so I hope that

accomplish this goal and so I hope that the next time you hear the phrase big

the next time you hear the phrase big

the next time you hear the phrase big data this will be what you think of

data this will be what you think of

data this will be what you think of because this is a future of social

because this is a future of social

because this is a future of social research in the digital age thank you

”

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