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Current time:0:00Total duration:4:00

- [Instructor] All right, we
have a wordy question here. The global temperature anomaly
indicates how much warmer or colder the average
global temperature is than normal during a particular time. A researcher conducting
an observational study charted and analyzed
atmospheric carbon dioxide, CO2, levels, and the global temperature anomaly in degrees Celsius since the year 1960. The researcher observed that the rate of, okay, this is the part this
seems to get interesting. The researcher observed
that the rate of increase of atmospheric CO2, carbon
dioxide, since 1960, approximately four percent per decade, is comparable to the rate of increase in the global temperature anomaly during the same time period,
approximately 3.9% per decade. Based on this data, which
conclusion is valid? All right, let's see. There is a correlation
between the increase in atmospheric CO2 levels since 1960 and the increase in the
global temperature anomaly during the same time period. That one seems pretty valid. These are both moving in
the same direction together. That's what correlation tells us. It doesn't mean that
necessarily the CO2 levels are causing the temperature increase or that the temperature
increase is causing the CO2 levels to increase. It's just saying that
look, over this time, we're seeing that these two
things are moving together, which is what correlation
is talking about. How much do these data
points move together? So I'm kind of, I'm liking
this one, I'm liking this one. So I'll, well actually,
let me read all of them before I pick that choice. The increase in the
global temperature anomaly since 1960 caused the
increase in atmospheric CO2 levels during the same time period. Well no, we don't know that. We don't know whether there
is causality here, whether, we haven't, just by looking at that data of these two things moving together, you can't say that the temperature caused the CO2 to move up. This is one of the classic things that a lot of times when
two things correlate, people want to show that
there's some causality. But it's much harder to show causality than it is to show correlation. So I definitely don't like that. The increase in atmospheric
CO2 levels since 1960 caused the increase in
global temperature anomaly during the same time period. Well that might be a
reasonable hypothesis, but that data doesn't tell us that. It doesn't tell us, there might
have been some other cause that caused both of those
two things to go up. Or this might have just been two things that happened to move
together but it wasn't, it wasn't because of any kind of causation one way or the other. So you can't say that just
based on the data that we have, the fact that they both
increased at roughly four percent per decade since 1960, you can't say that one caused the other. There is no correlation
between the increase in atmospheric CO2 levels
since 1960 and the increase in global temperature anomaly
during the same time period. No, there for sure is a correlation. You would say there's no correlation if in some years, the CO2,
some decades, CO2 went up and the, and the temperature went down, while in other decades, they both went up and in other decades, they both went down. That would be no correlation. If actually every time
one of them went up, the other one went down, that would be a negative correlation. If they move together,
that is just a very strong positive correlation, and
no correlation would be if you couldn't, you know,
sometimes when one moves up, the other one moves up or
down, and when the other one moves up or down, the
other one moves up or down. I don't know if that last
thing I said just made sense. But there was definitely a correlation. They were moving together. They were both increasing,
and roughly at the same rate, over per decade since 1960,
so I would rule that one out. So yep, feel good with our first choice.