Lesson video

Hello.

My name is Dr.

Rowlandson and I am happy to be helping you with your learning during today's lesson.

Let's get started.

Welcome to today's lesson from the unit of graphical representations of data.

This lesson is called Constructing Scatter Graphs by Utilising Technology.

And by the end of today's lesson, we'll be able to construct scatter graphs for data presented in a number of different ways using technology.

Here is a key word that you may be familiar with and we'll be using frequently in today's lesson.

This lesson contains two learn cycles, with each learn cycle looking at a different piece of software for constructing scatter graphs.

To begin with, let's start with constructing a scatter graph by using a spreadsheet.

Scatter graphs tend to be more useful when dealing with large amounts of data than they are when we're dealing with small amounts of data.

When we are learning to plot scatter graphs by hand, we may often practise plotting scatter graphs for small amounts of data to get a sense of what the process is.

However, trying to do that for large amounts of data gets very difficult.

For starters, constructing scatter graphs by hand can be a very, very slow process, so doing it for a large amount of data could take a long time.

Also, plotting scatter graphs by hand can be inaccurate as well, making it imprecise where the points are on the scatter graph.

So generally, it can be impractical to plot a scatter graph by hand for when we have large amounts of data, which is often what we are dealing with.

Luckily, technology can be a useful way to plot scatter graphs both quickly and accurately.

One type of technology that can help us plot scatter graphs is spreadsheet software.

Some examples of spreadsheet software include Google Sheets, Microsoft Excel, and Apple Numbers, but there are plenty other products available that are also allow you to plot scatter graphs using spreadsheets.

Now, this lesson will include some demonstrations for how to plot scatter graphs, and we'll be using Google Sheets for those demonstrations.

However, you might not use Google Sheets, you might use Microsoft Excel, for example, or Apple Numbers.

If that's the case, don't worry about it, 'cause while the demonstrations in this lesson use Google Sheets, other software usually have the same functions.

However, the buttons might just be in different places.

During this lesson, we'll be exploring a large dataset taken from the Met Office, and the data is about weather in the city of Bradford in England.

And the data's been taken on a monthly basis from 1941 all the way up to 2022.

And you can access a copy of this data by clicking on the link included in this presentation.

You'll need to to save a copy of this spreadsheet yourself in order to be able to make changes to it and also plot scatter graphs on it as well.

Let's take a look at what the data in this spreadsheet shows us.

To begin with, the first two columns have the year and the month for each row of data with month one being January, month two being February, and so on.

This next column tells us the mean of the daily maximum temperature for each month.

So a month, for example, with 30 days, they will have recorded the maximum temperature for each of those days in Bradford and then found the mean of those days, of those temperatures, and that is what is reported in this data.

The next column tells us the mean of the daily minimum temperatures for each month in Bradford.

In a similar sort of way, if a month, for example, has 30 days, they will have recorded the minimum temperature each of those 30 days, and then found the mean of those minimum temperatures, and that is what's reported in this data.

This next column tells us the total amount of rainfall throughout the month, and that is measured in millimetres.

And the last column tells us the total sunshine duration for each month, and that is measured in hours.

It is the amount of time that the sunshine was visible for each month.

Now, while all of the cells on this spreadsheet you can see here contain numbers and nothing but numbers, when this data was first downloaded from the Met Office website page for this lesson, that's not how the data appeared.

For example, many of the cells were blank because for one reason or another, the Met Office were not able to collect data about that particular measure for that month.

Another problem can be as well that some of the cells contained characters that were not numbers.

For example, in some of the cells, the numbers had asterisks next to 'em.

In this case, it was because that data for the Met Office was predicted data, hadn't been verified properly yet, so it was like an estimate for what that number would be.

And they show that by putting asterisk in.

So one problem you face when dealing with large amounts of data is deciding what it is you're gonna do with all these blank cells or characters that are not numbers.

In the case of this data, when there was a blank cell, a whole row was deleted.

And when there's a character such as an asterisk, just that character was deleted.

So that we have just numbers and no empty cells.

Let's look at plotting a scatter graph to represent the total rainfall and total sunshine hours for this data using a spreadsheets.

I'll first demonstrate using Google Sheets, and then I'll go through it again step by step.

Click on the column heading for column E to select all the data in that column.

And then while holding down the Control key, click on the column heading for F to select that data too.

Let's now insert a scatter graph.

Click on Insert and choose Chart.

In this case, it is automatically chosen a scatter graph for us because detected is bivariate data.

If it doesn't do this, we can go to chart type, look at all the different types of graphs that can be plotted and choose scatter graph.

We can see that the scatter graph has plotted total rainfall on the horizontal axis and total sunshine on the vertical axis.

Let's look at changing those now.

For the horizontal axis, go to where it says x-axis, click on the current variable, Total Rainfall, and choose Total Sunshine instead.

And for the vertical axis, we need to go to where it says series.

Click on the current variable, and click on Total Rainfall instead.

In this case, it switched around our data points, but not switched the labels on the axis, so we need to do that ourselves.

Click on customise.

Chart and axis titles.

Select where it says Chart title and change it to horizontal axis title.

And we need to type in total sunshine duration and our unit, which is hours.

And then do it again.

Choosing the vertical axis title and type in total rainfall and our units, millimetres.

Let's now go through that again step-by-step.

So to plot a scatter graph to represent the total rainfall and total sunshine hours, start by selecting the data we wanna use.

We could do that by clicking on the E column heading to select all the data in that column.

Hold down the Control key so we can then select other data while still highlighting the data we have.

Click on the F column heading.

So now, we have highlighted two columns.

And then click on Insert and then Chart.

In this case, with Google Sheets, it automatically chooses to plot a scatter graph because it detects we have bivariate data, two sets of measures in the same data.

If, when you do it, it does not do a scatter graph straight away, don't worry.

You can go on to set up, click chart type, scroll down for the different types of charts, and choose scatter graph.

In this example, the software has chosen the rainfall to go on the horizontal axis and the sunshine to go on the vertical axis, and that's because rainfall comes first before sunshine in the order of the columns.

We may want to change that.

To switch the axis, go to setup, go to where it says x-axis, and that'll be for the horizontal axis.

Click on the variable it currently has and then select total sunshine hours.

And then you can see it looks a bit odd at the moment, that's because we need to change the vertical axis.

So then click on where it says series, click on the variable and choose total rainfall.

Now, once again, we can see that the variables have not changed on the axis labels.

We can change those by going to customise.

Click on chart and axis titles.

For the title type selector, click horizontal axis title.

Type in the axis title you want, and then repeat it again for the vertical axis.

Let's check what we've learned so far.

Which option do you need to click to insert a scatter graph from the option shown? Is it A, insert sheet, B, insert chart, C, insert image, or D, insert drawing? Pause.

Make a choice and press play when you're ready for the answer.

The answer is B, insert a chart.

What do you click to choose a variable on the horizontal axis in this case? Is it A, chart type, B, x-axis, C, series, or D, switch row/columns? Pause the video, make a choice, and press play when you're ready for the answer.

The answer is B, x-axis.

What do you click in this menu to choose a variable for the vertical axis? Is it A, chart type, B, x-axis, C, series, or D, switch/slash columns? Pause video, make a choice, and press play when you're ready for the answer.

The answer is C, series.

Okay, over to you now for task A.

This task contains two questions.

And to complete the task, you'll need to have access to a computer with spreadsheet software and the link to the large data file, which is included in this presentation.

So question one, access the data for this task by clicking on the link for Bradford weather data.

Use that data to construct a scatter graph where the horizontal axis shows the total rainfall and the vertical axis shows the mean daily minimum temperature.

Pause the video, have a go, and press play when you're ready for question two.

And here's question two.

Once again, you'll need the large data file for Bradford's weather data.

There are two scatter graphs plotted below.

You can see what the vertical axis was each scatter graph, but you can't see what the horizontal axis was for each one.

Your job is to work out what goes on the horizontal axis for each of these scatter graphs.

You can do it by plotting different scatter graphs using whatever it says in the vertical axis, trying different measures for your horizontal axis until you get a scatter graph that looks like the one below.

Once you've done that, write down which measure goes on the horizontal axis for that scatter graph.

Pause the video, have a go, and press play when you're ready for the answers.

Well done with that.

Here is what your scatter graph should look like now for question one.

It may be that your scatter graph is more zoomed in or more zoomed out on one of the axis, but generally, the shape should be the same as what we can see here.

And here are the answers for question two.

In the first graph, the horizontal axis was for total sunshine duration in hours.

Now, on the second scatter graph, the horizontal axis was for the mean maximum daily temperature.

Well done so far.

Let's now go on to the second cycle for today's lesson, which is about constructing scatter graphs by using Desmos.

Desmos is a website page that can be used to plot graphs of many different types, including scatter graphs.

To get started with Desmos, you'll need to open up a web browser and go to desmos.

com.

And then find a button that says graphing calculator and click it.

You'll also need to have access to a large data file as well.

So open up a separate browser window or separate browser tab and click on the link that is available at the bottom of this presentation.

This particular data file is for UK weather data.

We're going to now use Desmos to plot a scatter graph to represent the total sunshine duration and the mean daily minimum temperature for Bradford's data.

And like previously, I'm gonna demonstrate the whole process in full and then go through it again with step-by-step instructions.

First, check that we have the data tab for Bradford open.

Let's select the data for total sunshine duration by clicking on the column heading.

Then while holding Control, click on the column heading for mean of daily minimum temperature.

Copy that data, which can be done by holding Control and pressing C or using a different shortcut.

Go to Desmos.

In the first empty cell, paste in the data, which can be done by by holding Control and pressing V.

And Desmos has automatically plotted a scatter graph for us.

Let's now label our axis.

So go to the spanner in the top right corner.

Go to where it says x-axis.

And let's type in our label here, which is total sunshine duration and our units, which is hours.

And then click on y-axis, and it's the mean of the daily minimum temperature and our units, which is degrees Celsius.

The points are currently green.

Let's change those by going to that first data cell where it says Y1.

Click and hold the circle until option menu appears and choose the colour you want.

In this case, black.

This scatter graph shows the weather data for the city of Bradford.

We can insert weather data for another city now by first going back to our spreadsheets, go into the tab for Lerwick's data.

Selecting the same data again, total sunshine duration and mean of minimum temperature.

Copying it.

Control and C will do that.

Going back to Desmos.

And in the second data cell, paste the Lerwick data in.

For example, with Control and V.

And it has now pasted in points for Lerwick's weather data.

And we can see that the colour of those points is different.

So we can see the points for Bradford in black and Lerwick in blue.

Let's go through those steps again.

We first need to go to our spreadsheet.

Make sure that the Bradford tab is selected at the bottom of the screen, so we're using the Bradford data.

Select the data columns as previously shown by clicking on the column headings, holding Control.

And then copy the data by using a shortcut such as holding down Control key and pressing C.

We then need to go to Desmos and paste the data in.

So click on the first open cell in the side panel, pasting the data by using a shortcut such as Control key and pressing V, and that'll paste in a table showing both sets of values and automatically plot a scatter graph.

If we want to label the axis on our scatter graph, we'll need to click on the spanner symbol at the top right hand corner.

And then where it says x-axis, click on label and type in what you want the label to be.

And the same for the y-axis as well.

You can also change the colour of the points on our scatter graphs too.

We do this by going to the table in the side panel, clicking on the the point symbol next to it says Y1.

Click and hold it until a options box appears.

And then from there, you can choose which colour you want.

And on the same graph, we can plot data for another city.

We can do it for the data for Lerwick, for example.

So go back to the spreadsheet, make sure that the Lerwick tab at the bottom is selected, so we can see the Lerwick data.

Highlight the same data columns as previously in the same way, and copy it.

Then go to Desmos, and in the second open cell in the side panel, paste in that data and it'll automatically construct a scatter graph for those points on top of the points of Bradford as well.

So we can see now the points for Bradford and Lerwick are in different colours.

Okay, let's check what we've learned there.

How do you copy data after the columns have been highlighted? What is the shortcut for it? Is the answer A, pressing the Control key and then pressing the C key? Is it B, holding down the Control key and then pressing the C key? Is it C, pressing the Control key and then pressing the V key? Or is it D, holding down the Control key and then pressing the V key? Pause the video, make a choice, and press play when you're ready for the answer.

The answer is B.

To copy data after it's been highlighted, we need to hold down the Control key and press the C key while it's held down.

How do you paste data after the columns have been highlighted? Same answers available.

Pause the video, make a choice, and press play when you're ready for the answer.

The answer is D.

Hold down a Control key and press V while you're doing it, and that'll paste in whatever you've copied.

And true or false.

After you paste bivariate data into Desmos, you need to then click insert and chart to plot the scatter graph.

Is that true or false? And justify your answer with one of the two options below.

A, Desmos plots a scatter graph automatically when you paste in the data.

Or B, you need to tell Desmos that you want to plot a chart with the data before choosing scatter graph.

Pause video, make your choices, and press play when you're ready to continue.

The answer is false, because Desmos plots a scatter graph automatically when you paste in bivariate data.

Okay, over to you now for task B.

Once again, you'll need access to spreadsheet software and also access to the large data file, which is linked in this presentation.

The data file is UK weather data.

The task contains two questions.

In question one, construct a scatter graph for Bradford's data with the horizontal axis showing total rainfall and the vertical axis showing total sunshine hours and do this in Desmos.

Pause the video, have a go, and press play when you're ready for question two.

Here is question two.

It has three parts.

Part A, construct a scatter graph for Armagh's data with the horizontal axis showing total sunshine duration and the vertical axis showing the mean of a daily maximum temperature.

And then part B, on that same scatter graph, plot the same data for Lerwick and make sure the points for Lerwick are different colour to Armagh's data.

And then for part C, take a look at your scatter graph.

Look at the points for Lerwick, look at the points for Armagh, and decide which town do you think tends to get the warmest out of those two towns? Pause the video, have a go, and press play when you're ready for the answers.

Well done with that.

Here is what question one should look like after you plot a scatter graph on Desmos.

It should have the same shape generally as the scatter graph you plotted in task A using a spreadsheet 'cause it's the same data, just different software.

Let's now go through the answers to question two.

In part A, when we plot a scatter graph for Armagh's data, it should look something like the one we can see here.

The points in this graph are purple for Armagh data.

The points on yours might be a different colour, and that's okay.

But for these examples, Armagh's data is purple.

And then in question B, when we paste on Lerwick data, it should look something like this.

Here, we have Lerwick's data in green and Armagh's data in purple.

We can see two distinct sets of data overlaying each other.

And then in part C, if we look at the scatter graph, we can see that many of the points which are representing Armagh's data tend to be higher up in the vertical direction than many of the points representing Lerwick's data.

Not all of them, but a lot of the points for Armagh are higher than the points for Lerwick.

That means that generally Armagh tends to be warmer overall than Lerwick.

Fantastic work today.

Great job.

Here's a summary of what we've learned in today's lesson.

We've learned that scatter graphs can be constructed both quickly and accurately using spreadsheet software such as Google Sheets, Microsoft Excel, Apple Numbers, or whichever spreadsheet software you use.

We've learned that scatter graphs can also be plotted using Desmos.

And while we've been plotting scatter graphs, we've learned that change in which axis is used for which variable can affect how the scatter graph looks as well.

Well done.