USGS Data Management

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Analyze
U.S. Geological Survey Data Lifecycle Diagram Plan Acquire Process Analyze Preserve Publish/Share Manage Quality Describe (Metadata, Documentation) Backup & Secure The USGS Science Data Lifecycle

Data Management: Analysis

The Analyze stage of the Science Data Lifecycle represents activities associated with the exploration and assessment of data, where hypotheses are tested, discoveries are made, and conclusions are drawn. Data analysis may also be less targeted and deal with interpretation of data to better understand content, context, and quality. In this stage of the Lifecycle, conclusions or new datasets are generated and methods are documented. Analytical activities include statistical analysis, spatial analysis, modeling, visualization, image analysis, and interpretation among others.

The Analyze Stage Can Trigger Additional Data Acquisitions and Processing

Key Points

  • The analyze step is about using tools, models, or statistical procedures on data to answer science questions.
  • Documentation of the analysis should be provided so that any potential user can reproduce it.
  • Select analytical methods and techniques appropriate to your discipline.
  • Ensure quality and provenance of the data throughout the analysis activities.

Frequently the exploration and interpretation of data at the Analysis stage of the data lifecycle reveals additional data acquisitions or processing needed to meet the goals of a research project. See the Data Lifecycle Overview.

Process and Analyze are closely related activities when performing scientific research

It can sometimes be difficult to determine where processing ends and analysis begins. In part this is because the two concepts are often intermingled to ensure that both data and research products meet a common set of goals. Learn more about the considerations for both process and analyze activities.

Statistical Analysis

Statistical methods are applied to data to derive patterns, make generalizations, detect trends, and to estimate the uncertainty associated with the data. Many methods appropriate to work at the USGS, both within and beyond hydrology, can be found in the classic 2002 reference book by Helsel and Hirsch, "Statistical Methods in Water Resources."

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Visualization

Graphical representations of events or scientific data enhance our understanding. These may be static images that show a pattern or clarify the connections between elements in a complex system; animated graphics and videos; or maps that show data in different ways.

Spatial Analysis

According to the Esri GIS Dictionary, spatial analysis is "the process of examining the locations, attributes, and relationships of features in spatial data through overlay and other analytical techniques in order to address a question or gain useful knowledge. Spatial analysis extracts or creates new information from spatial data." A good resource for understanding spatial analysis can be found in the USGS report, "A Practical Primer on Geostatistics."

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Image Analysis

Analytic methods for detection of objects and patterns within images are used to identify features and derive time-based information that is difficult or impossible to obtain in other ways.

Modeling

Models are tools (usually software) for abstraction and simplification of natural systems that allow us to describe and explore those systems and make predictions about system behavior.

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Interpretation

Interpretation is the act of using data and analytic output to evaluate hypotheses and methods, extrapolate from observations to predictions, detect patterns, and explore the consequences of assumptions. The term 'interpretive' has special meaning within the USGS; see the USGS Fundamental Science Practices site for an explanation and examples of interpretive and noninterpretive data products.

Analysis Documentation

Reproducible science is a foundation of our scientific work. Sufficient documentation of analysis methods in support of reproducibility is required. Documentation of analytic methods and techniques is usually included in published works such as methods papers, research publications, and journal articles. Search the USGS Publications Warehouse for Analysis examples covering topics of specific interest.

What the U.S. Geological Survey Manual Requires:

Policies that apply to the Analyze stage largely deal with making sure there is appropriate documentation of the tools and methods used in analysis, and that the analyses directly result from the data acquired and processed.

The USGS Manual Chapter 500.25 - USGS Scientific Integrity discusses the USGS’s dedication to “preserving the integrity of the scientific activities it conducts and that are conducted on its behalf” by adhering to Department of Interior 305 DM 3 - Integrity of Scientific and Scholarly Activities.

The USGS Manual Chapter 502.2 - Fundamental Science Practices: Planning and Conducting Data Collection and Research includes requirements for process documentation of analytical methods and techniques.

"Documentation: Data collected for publication in databases or information products, regardless of the manner in which they are published (such as USGS reports, journal articles, and Web pages), must be documented to describe the methods or techniques used to collect, process, and analyze data (including computer modeling software and tools produced by USGS); the structure of the output; description of accuracy and precision; standards for metadata; and methods of quality assurance."

The USGS Manual Chapter 502.4 - Fundamental Science Practices: Review, Approval, and Release of Information Products addresses documentation of the methodology used to create data and generate research results.

"Methods used to collect data and produce results must be defensible and adequately documented."