Welcome to MySecretMathTutor, For this video I want to show you how to make
a line chart. But before we get too far, let's go ahead
and talk a little bit about what makes a line chart.
In a line chart we often use these to show how the data changes over a period of time, and a
real key feature of these is that we essentially take a scatter plot and we use line segments
to connect the actual data values. Now again, this is really good to see how
the data changes over time, because we can see if the data is going up or going down, or really
what's its doing, or look for trends. Along the bottom, this is our x-axis.
This is where we usually use some sort of time.
Remember it doesn't necessarily have to be, but usually that's what we use these for.
And of course our y-axis will be our vertical line.
Alright, let's give our example a try and see how we can actually build this thing
For the example I want to look at how many
students are enrolled in a particular school. So I'm looking at the year, and how many students
are actually enrolled. The very first thing I want to do is probably
set up my years along the bottom of my chart here.
All of my years are between 1990 and 2008 so I'm going to end up scaling these so I
don't have to, you know, show all of the years on here.
We'll go ahead and start with like the first year being 1990, and then go from there.
1990, we'll have one for 92, 94, 96, 98, 2000, 02, 04, 06, 08.
Alright, so I'll mark this as 90, 92, 94, 96, 98, this will be 2000, 2002, 2004, 2006,
2008. Alright, so on the bottom we'll mark this
as our years. Along the other side all of our values, it
looks like are definitely over 1000, I don't want to have to show all of those, or else
you know, if I did a tick mark all the way from zero all the way up to 1000, most of our data
points would be really really near the top, and really close together.
I want to see definite changes in here, so we'll scale those a little bit as well.
Let's see. My first tick mark here, we'll go ahead and say that is say 1100, maybe
we'll put our zero at 1000, and go up from there.
1200, 1300, ... There now we should be able to capture all
of that data pretty good. Alright, so the very first part of this is
to take these data points and put them on our chart.
Then we'll go ahead and connect them with nice line segments to see how the data is changing.
So starting with the first one, here is our 1990.
We need to put a spot at 1103, which is just
a hair above 1100. So that looks like a good spot.
For 92, its over 1500. 1528, so just again a hair over that one.
For 94, 1390. Let's see, 1391. OK, we'll say its right about there.
96, 1002. Oh boy. That just like right there. Just a hair above the 1000 mark.
98, 1345. Let's put that one right about there. Year 2000, 1271. There looks good.
1232, oh a little bit shorter than that previous one.
Not a whole lot. 1217, really close to that 1200 mark.
Here is 06, 1340. So just a hair above the 1300 mark.
And the year 2008, 1344. So almost the same but just a little bit larger than our previous dot.
OK, so we can definitely see all of our data points.
They look like they are kind of scattered
all over the place, let's go ahead and connect them using those nice strait line segments.
Usually it helps out to do this with a ruler, but if they are not that far away, usually
you can make a pretty good strait line. Let's see, can't forget this data value way
down here. OK, and now we've actually created our line chart.
Now time to interpret exact what's going on here.
Well, we can see that with enrollment, it
looks like its staying about the same. There are a few years where it's just going
up by a little bit. And a few years where it's going down by just
a little bit. One particular year, 1996, there is a huge
drop in enrollment. Other than that, everything seems to be staying
about even, not really changing a whole lot. So you know, maybe enrollment not going anywhere,
not really doing a whole lot of stuff. So we can see those changes as we start moving
our through the years. Alright, and that's how you make a line chart.
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