Comparative Analysis of Scientific Data: Definition & Example

Instructor: Marc Chiacchio

Marc has taught Bachelor level students climate science and has a PhD in climate science.

Comparative analysis compares two or more datasets in order to support a hypothesis or theory. In this lesson, we discuss the definition of this term and how it is applied by using an example of changes in the Earth's temperature.

Scientific Analysis

Did you ever wonder how samples of data are analyzed in order to make valid scientific claims that the Earth is warming? Once temperature datasets are collected in digital format, comparative analysis can be applied. This type of analysis simply compares one or more datasets to determine their consistency with one another.

If a consistency is found between the datasets, then it adds support to a scientific claim. Such techniques can involve a statistical test called correlation, which is a quantitative figure measuring the interdependence of variables. This figure contains a quantity between 0 and 1. The closer the correlation is to 1 between two datasets, the stronger their interdependence.

Comparative analysis also includes a technique to visually inspect the data. This is accomplished by constructing a time series, which is a series of connected values at certain points through time on a graph. By visually observing the trends (measure of the change in that quantity through time) in the time series, you can determine if the datasets have a consistency or not.

Example of a time series for the global temperature and carbon dioxide.

In the next section, we discuss what major datasets are used in comparative analysis to monitor changes in the Earth's temperature. Whenever someone debates climate change, they are referring to these datasets.

Datasets Used for Studying Global Temperature

These days, anyone with a computer can download scientific data and graph data points for a comparative analysis. Using the example of the Earth's temperature, we first need to know the datasets used in the study of the Earth's global temperature. When we see that a dataset doesn't agree with the others, it can be difficult to interpret our findings and identify the sources of error involved.

When discussing climate change, there are three scientific datasets that refer to surface temperature estimates:

  1. HadCRU (Hadley Centre/Climate Research Unit)
  2. NOAA (National Oceanographic Atmospheric Administration
  3. NASA GISS (Goddard Institute for Space Studies)

Analysis of Earth's Global Temperature

Now that you are familiar with the different datasets used to study the temperature of the Earth, we will see how to apply comparative analysis on them. Once they are downloaded digitally, the datasets are graphed on a computer with connecting lines that go through their data points. These three datasets do not span over the same time period. The HadCRU begins in 1850 while the NOAA and NASA GISS start in 1880.

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