How Much Data is Enough?

Overview

Given sets of graphable data students will show that various viewpoints can be supported depending on how data is presented and interpreted. These may or may not be accurate or relevant representations of data results over time. This lesson contains basic graphing components, interpretation of information and communication to others of findings depicted in graphs. Teachers may choose to use either the total lesson or bits and pieces depending on student abilities and time constraints. The lesson is also designed so that it can be expanded for advanced students and used as an enrichment activity or a remedial activity.

Objective

Given a set of data students will:

1. Create an appropriate graph using Microsoft Excel or another graphing program.
2. Answer questions related to the data using the completed graphs.
3. Interpret the information found on the graph, and present either orally or in a written format, their findings
4. Determine the mean, median, mode and range of the data
5. Enrichment Activity: Consider and discuss the question of "When Do Scientists Have Enough Information To Answer a Question?"

Preparation

See the Resources section for Background information. Use of Microsoft Excel or another computerized graphing program will speed the activity and allow for more than one set of data to be examined. Graph paper and calculator can also be used by the students to get the same results.

If groups are given different data sets, the graphs can be printed or displayed so that the entire class or several groups can merge their information to come up with findings.

Procedure

1. Download the data set from the materials section.
2. Using your chosen (or assigned by teacher) data section (ex. 1951-1980), construct a graph of the annual temperature anomaly versus the year.
3. Add a trend line to this data. Be careful to observe what is happening to the line.
4. Make a new graph to look at the entire data set (1856-2005). Be sure to plot a trend line on this graph as well.
5. Answer Student Questions in Part I (attached)
6. Complete Graphic Interpretation in Part 2 (attached)

Resources

Background Information for Teachers: The debate exists about the occurrence of climate change and its severity across the globe. Temperature observations from both land-based and ocean-based stations have increased greatly in the last century with tens of thousands of reporting stations presently in place. Using data from P.D. Jones et al. and information from the Climate Research Unit (CRU) we will be looking at temperature fluctuations over time. The data begins with readings from 1856 through 2005 and is listing the temperature anomalies, or deviations from a mean. In this case, the mean is coming from the 30-year period 1961-1990. The data is then measured against whether the temperature increased or decreased from that mean and listed as the departure from the mean.

Example: If the mean yearly temperature for the 30-year period 1961-1990 was 65 degrees, the mean from 1856 will be measured against that. If the temperature were lower than the 1961-1990 mean you will get a negative anomaly (negative number), if it is warmer you will see a positive anomaly.

"Hook": Have you ever looked at graphs on the news or in newspapers where you are told that certain trends are occurring and that something negative, or positive, is going to happen as a result? Using the same set of numbers it is quite possible to make things look just a little different to help push your point of view. This activity will allow you to determine some "right" answers about temperature data and discuss/defend your position.

Tips and Tricks: Try the activities yourself first! It will greatly reduce the frustrations with using Microsoft Excel, especially for the inexperienced. This activity may also be used in a math class to practice graphing techniques as well as finding the equation of a line.

Vocabulary

anomaly: a deviation from the common rule, type, arrangement, mean, or form.

deviation: departure from a standard or norm.

global warming: an increase in the earth's average atmospheric temperature that causes corresponding changes in climate and that may result from the greenhouse effect.

climate change: any long-term significant change in the weather patterns of an area.

Key Questions to Consider with Students

1. How can a set of data be used to represent multiple view points regarding a specific topic?
2. What evidence can be provided to present arguments for or against global warming?
3. Given a set of data, are you able to create a graphic representation?
4. How does the amount of data examined over a given period of time affect the trends observed?
5. How does a person distinguish how much data is needed to accurately display trends over time?

Further Resources:

Jones, P.D., D.E. Parker, T.J. Osborn, and K.R. Briffa. 2006. Global and hemispheric temperature anomalies--land and marine instrumental records. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A. http://cdiac.ornl.gov/trends/temp/jonescru/jones.html (source of data in attached Excel file)

Credits

Brandon Gillette, bgilletteon [at] olatheschools.com