Name:__________________________________
Using Data from Public Sources
Data are the actual measurements that scientists take during an experiment, the concrete
values that they will then investigate to draw conclusions about their research. Data are what
scientists use to convince other people that their theories are correct. They generate graphs from
their data to make it easier to understand. Many scientists collect their own data, but there are
also many sources of publicly available data collected by large institutions and programs that
scientists use to test hypotheses. We will use publicly available data about the climate to make
our own graphs to think about the topic of climate change. Bear in mind a hypothesis is just an
educated guess; the data may or may not agree with the hypothesis. When data agree with the
hypothesis scientists say it supports their hypothesis. When the data don’t agree they say it
refutes their hypothesis.
After opening the Excel file with the climate data, notice several things:
 The first row of every column tells you what the variable in that column is. You have
many variables to work with, and you have data for many years.
 Some of the variables have long names and do not fit in the cell. You can read the entire
name by clicking on the cell.
 Most rows have values missing for some of the dates. This is normal, scientists have to
work with incomplete datasets all the time.
 If you scroll down in the sheet there are more numbers than you can view all at once, this
is also very common.
 There are many numbers! Don’t be overwhelmed; make graphs and charts to make the
numbers easier to understand.
Part I: Using Excel to organize numbers and make graphs
1. Each row (horizontal) is identified by a number, and each column (vertical) is identified
by a letter. Which column contains the variable Year? What is the range of years
included in your dataset (you will have to scroll down)?
Column A, years 1955-2013
2. How many different variables (including year) do you have in this dataset?
13
3. Some variable names are too long to fit in one cell. You can read the entire name by
clicking on the cell that contains it. Which column contains the variable Avg Temp
Burlington VT (F)?
Column B
Name:__________________________________
4. If we are interested in both year and temperature in Burlington, which is the independent
variable and which is the dependent variable?
Year: Independent, Temperature: Dependent
5. Form a hypothesis about Avg Temp Burlington VT and Year that you could test by
graphing these variables.
Many possible answers, but an example:
With what we know about climate change, average temperature in Burlington may have
over time since 1955.
6. Using the “Charts” section, make a pie chart of the values in Avg Temp Burlington VT
(F).
a. Is this an appropriate graph for these values?
No
b. Why or why not? What does this graph tell you?
This chart shows that each temperature value occurs once, with no information
(unless you scroll over) about what the temperature actually was.
7. Make a column graph of the values in Avg Temp Burlington VT (F).
a. Is this an appropriate graph for these values?
Yes
b. Why or why not? What does this graph tell you?
This graph shows what the temperature value was in each year, so by looking at
where the values are on the y-axis we can get an idea of what the average
temperatures are. The large
c. What is another variable you could include in this graph to make it more
informative?
Including year in this visualization on the x-axis would help us understand the
temperature trends over time.
8. Make a line graph of the values in Avg Temp Burlington VT (F).
a. Is this an appropriate graph for these values?
Yes.
Name:__________________________________
b. Why or why not? What does this graph tell you?
This graph connects consecutive values in the column (which in this case are
consecutive years). This helps us see the trend in the data, even though the x-axis
is only labeled as column values, not years.
c. What is another variable you could include in this graph to make it more
informative?
Including year in this visualization on the x-axis would help us understand the
temperature trends over time.
9. Which of the graphs you created do you think is the best for displaying these data?
Line graph.
Part II: Investigating your own hypothesis:
10. What is a hypothesis you could test by graphing one or more of these variables?
Many possibilities. One example:
The temperature in one part of the country may affect the precipitation somewhere else
because of distance weather and cloud sources. The temperature in Seattle, WA may
correlate with the precipitation in Burlington, VT.
11. What is your independent variable? What is your dependent variable?
Temperature in Seattle – Independent
Precipitation in Burlington – Dependent
12. Make the appropriate graph to test this hypothesis. Make sure you label the axes, give it a
title, and make the values in the axes appropriate ranges. Print this and staple it to the
back of this worksheet.
See last page
13. Explain why the graph you chose is the best option for the variable(s) you are interested
in (it may be easier to explain why other graphs aren’t the best option).
I plotted temperature (the independent variable) on the x-axis and precipitation
(dependent variable) on the y-axis. This will show if the precipitation changes in
response to increasing temperature. I used an XY scatterplot because this shows how two
variables correlate with each other, and added a trendline to see whether there was any
Name:__________________________________
positive or negative association. This trendline is flat, indicating no relationship between
the two variables.
14. Summarize the message your graph says about the data in one sentence (if this were your
science fair project, you would put this in the text of your results).
There is no (statistical) relationship between the average annual temperature in Seattle,
WA and the precipitation in Burlington, VT.
15. Based on what you said in question 13, do the data in your graph support or refute your
hypothesis in question 10?
No, the data do not support my hypothesis. I hypothesized there would be a relationship
between these two variables and there was not.
Name:__________________________________