How to spot a misleading graph - Lea Gaslowitz

Kako prepoznati obmanjujući grafikon - Lea Gaslovic

3,014,091 views ・ 2017-07-06

TED-Ed


Please double-click on the English subtitles below to play the video.

Prevodilac: Ivana Krivokuća Lektor: Tijana Mihajlović
00:07
A toothpaste brand claims their product will destroy more plaque
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Marka zubne paste tvrdi da će njihov proizvod uništiti više plaka
00:10
than any product ever made.
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od bilo kog proizvoda koji je ikada napravljen.
00:12
A politician tells you their plan will create the most jobs.
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Političar vam kaže da će njegov plan stvoriti najviše poslova.
00:16
We're so used to hearing these kinds of exaggerations
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Toliko smo navikli da slušamo ovakva preterivanja
00:18
in advertising and politics
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u reklamama i politici
00:20
that we might not even bat an eye.
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da se možda nećemo ni osvrnuti.
Ali šta ako tvrdnju prati grafikon?
00:23
But what about when the claim is accompanied by a graph?
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Na kraju krajeva, grafikon nije mišljenje.
00:26
Afterall, a graph isn't an opinion.
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00:28
It represents cold, hard numbers, and who can argue with those?
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On predstavlja suve, čvrste brojke, a ko može tome da se suprotstavi?
00:32
Yet, as it turns out, there are plenty of ways graphs can mislead
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Ipak, kako se ispostavilo, mnogo je načina na koje grafikoni mogu obmanjivati
00:36
and outright manipulate.
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i načisto manipulisati.
Evo nekih stvari na koje treba obratiti pažnju.
00:38
Here are some things to look out for.
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00:40
In this 1992 ad, Chevy claimed to make the most reliable trucks in America
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U ovoj reklami iz 1992. godine,
Ševrolet je tvrdio da pravi najpouzdanije kamione u Americi,
00:45
using this graph.
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koristeći ovaj grafikon.
00:47
Not only does it show that 98% of all Chevy trucks sold in the last ten years
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Ne samo da pokazuje da je 98% svih Ševroletovih kamiona
prodatih u poslednjih deset godina još uvek na putevima,
00:51
are still on the road,
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00:53
but it looks like they're twice as dependable as Toyota trucks.
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već izgleda kao da su dvostruko pouzdaniji od Tojotinih kamiona.
00:57
That is, until you take a closer look at the numbers on the left
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Odnosno, dok ne pogledate malo bolje brojeve na levoj strani
01:00
and see that the figure for Toyota is about 96.5%.
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i vidite da je Tojotina cifra oko 96,5%.
01:05
The scale only goes between 95 and 100%.
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Skala je samo između 95 i 100%.
01:09
If it went from 0 to 100, it would look like this.
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Kada bi išla od 0 do 100, to bi izgledalo ovako.
01:12
This is one of the most common ways graphs misrepresent data,
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Ovo je jedan od najčešćih načina na koje grafikoni lažno prikazuju podatke,
01:16
by distorting the scale.
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time što izvitopere skalu.
01:18
Zooming in on a small portion of the y-axis
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Uveličavanje malog dela ose ispilon,
01:20
exaggerates a barely detectable difference between the things being compared.
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znatno pojačava jedva primetnu razliku između stvari koje se upoređuju.
01:25
And it's especially misleading with bar graphs
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A pogotovo je obmanjujuće uz stubičaste grafikone
01:27
since we assume the difference in the size of the bars
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jer pretpostavljamo da je razlika u veličini stubića
proporcionalna vrednostima.
01:31
is proportional to the values.
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Skala se takođe može iskriviti duž ose iks,
01:33
But the scale can also be distorted along the x-axis,
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01:36
usually in line graphs showing something changing over time.
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obično kod linijskih grafikona koji pokazuju nešto što se menja vremenom.
01:40
This chart showing the rise in American unemployment from 2008 to 2010
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Ovaj grafikon koji pokazuje rast nezaposlenosti u Americi
od 2008. do 2010. godine
01:44
manipulates the x-axis in two ways.
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manipuliše osom iks na dva načina.
01:47
First of all, the scale is inconsistent,
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Pre svega, skala je nedosledna,
01:50
compressing the 15-month span after March 2009
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jer sažima period od 15 meseci nakon marta 2009. godine
01:53
to look shorter than the preceding six months.
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tako da izgleda kraće nego prethodnih šest meseci.
01:56
Using more consistent data points gives a different picture
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Korišćenje doslednijih podataka daje drugačiju sliku,
pri čemu broj gubitaka poslova opada do kraja 2009. godine.
02:00
with job losses tapering off by the end of 2009.
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02:03
And if you wonder why they were increasing in the first place,
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Ako se pitate zašto je uopšte rastao,
02:06
the timeline starts immediately after the U.S.'s biggest financial collapse
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vremenski okvir počinje odmah nakon najvećeg finansijskog kolapsa u SAD-u
02:10
since the Great Depression.
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od Velike depresije.
02:12
These techniques are known as cherry picking.
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Ove tehnike su poznate kao selektivno dokazivanje.
02:15
A time range can be carefully chosen to exclude the impact of a major event
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Vremenski opseg može biti pažljivo odabran tako da isključi uticaj velikog događaja
02:18
right outside it.
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neposredno izvan njega.
02:20
And picking specific data points can hide important changes in between.
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Odabir određenih podataka može sakriti važne promene u međuperiodu.
02:24
Even when there's nothing wrong with the graph itself,
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Čak i kada ništa nije pogrešno u samom grafikonu,
02:27
leaving out relevant data can give a misleading impression.
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izostavljanje relevantnih podataka može dati pogrešan utisak.
02:30
This chart of how many people watch the Super Bowl each year
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Ovaj grafikon sa brojem ljudi koji gledaju Superboul svake godine
02:33
makes it look like the event's popularity is exploding.
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daje utisak da je popularnost ovog događaja buknula.
02:37
But it's not accounting for population growth.
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Međutim, ne uzima u obzir rast populacije.
02:40
The ratings have actually held steady
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Gledanost je zapravo ostala stabilna
02:41
because while the number of football fans has increased,
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jer, dok je rastao broj obožavatelja fudbala,
njihov udeo u ukupnom broju gledalaca nije.
02:45
their share of overall viewership has not.
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02:47
Finally, a graph can't tell you much
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Najzad, grafikon vam ne može mnogo toga reći
02:49
if you don't know the full significance of what's being presented.
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ako ne poznajete u celosti značaj onoga što je prikazano.
02:53
Both of the following graphs use the same ocean temperature data
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Oba sledeća grafika koriste iste podatke o temperaturi okeana
02:56
from the National Centers for Environmental Information.
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iz Nacionalnh centara za informacije o životnoj sredini.
02:59
So why do they seem to give opposite impressions?
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Pa zašto se čini da daju suprotne utiske?
03:02
The first graph plots the average annual ocean temperature
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Prvi grafikon prikazuje prosečnu godišnju temperaturu okeana
03:05
from 1880 to 2016,
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od 1880. do 2016. godine,
03:07
making the change look insignificant.
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zbog čega promena ne deluje značajno.
Ali, u stvari, čak i porast od pola stepena Celzijusa
03:10
But in fact, a rise of even half a degree Celsius
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03:12
can cause massive ecological disruption.
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može izazvati ogromne ekološke poremećaje.
03:15
This is why the second graph,
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Zato je drugi grafikon,
03:17
which show the average temperature variation each year,
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koji prikazuje prosečno variranje temperature svake godine,
03:19
is far more significant.
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mnogo značajniji.
03:22
When they're used well, graphs can help us intuitively grasp complex data.
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Kada se dobro koriste,
grafikoni nam mogu pomoći da intuitivno shvatimo kompleksne podatke.
03:27
But as visual software has enabled more usage of graphs throughout all media,
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Međutim, vizuelni softver je omogućio veću upotrebu grafikona u svim medijima,
03:31
it's also made them easier to use in a careless or dishonest way.
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ali je i olakšao njihovo korišćenje na nepažljiv ili nepošten način.
03:35
So the next time you see a graph, don't be swayed by the lines and curves.
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Dakle, sledeći put kada vidite grafikon,
ne upravljajte se prema pravama i krivuljama.
03:39
Look at the labels,
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Pogledajte oznake,
03:40
the numbers,
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brojeve,
03:42
the scale,
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skalu
i kontekst,
03:43
and the context,
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03:44
and ask what story the picture is trying to tell.
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i zapitajte se kakvu priču ta slika pokušava da prenese.
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