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C R C logo Handbook of Chemistry and Physics Online


Section: 0 | On the Evaluation of Chemistry and Physics Data |
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How to Cite this Reference
The recommended form of citation is:
John R. Rumble, ed., CRC Handbook of Chemistry and Physics, 103rd Edition (Internet Version 2022), CRC Press/Taylor & Francis, Boca Raton, FL.
If a specific table is cited, use the format: "Physical Constants of Organic Compounds," in CRC Handbook of Chemistry and Physics, 103rd Edition (Internet Version 2022), John R. Rumble, ed., CRC Press/Taylor & Francis, Boca Raton, FL.

ON THE EVALUATION OF CHEMISTRY AND PHYSICS DATA

Over its 103 editions, the CRC Handbook of Chemistry and Physics has published an enormous variety of data sets in chemistry, physics, and related topics. The common feature among all these data sets is the devotion the CRC Handbook Editors have made to select the highest quality data available. Generations of CRC Handbook users have come to rely on the judgment and expertise of our Contributing Authors and Editors in evaluating available data to achieve the required quality. Let us take a moment to describe the process of data evaluation.

The evaluation of scientific data comprises three distinct approaches to reviewing reports of available measurements and calculations. For the sake of brevity, we will use the term measurement to include data resulting from physical measurements, modeling and simulation, and computational calculations in the following discussion, unless otherwise noted. The three evaluation approaches ask the following questions.

1. Does the measurement report identify which independent variables are important to the result and does it demonstrate how those variables were controlled during the measurement process?
2. Do the reported measurement results follow known laws of nature or established empirical relationships?
3. How well do the reported measurement results agree with other reported measurement results?

The relevant importance of the three approaches depends on the maturity of the scientific topic involved. For example, the independent variables important in thermodynamic measurements have been known for many decades, and new reports usually just need to refer to previous measurement methods. In contrast, however, measurements on nanomaterials are much newer and less standardized, and information about which independent variables have been controlled must be more detailed.

The CRC Handbook currently has data on close to 400 different topics compiled and evaluated by topic experts in academia, government research laboratories, and industry. A list of current contributors is included in the front material of each edition of the CRC Handbook, and the contributions of past authors can be found in previous editions.

Regardless of topic, the evaluation process is remarkably similar. The evaluators (authors) are selected because of their broad expertise in a topic. Because most chemical and physical properties can be measured using diverse methods, evaluators must be knowledgeable about all techniques used. The evaluation begins with gathering all relevant measurement reports and compiling the reported data. Such compilations include reported measured property values, metadata about the report, and information about the measurement technique(s) such as which independent variables were monitored during the measurement process and the reported uncertainties. When the data are assembled, the evaluator reviews each individual measurement results as well as the data set in its entirety. For each topic covered in the CRC Handbook, references are given so users can review the process used to arrive at the included evaluated data set.

While good measurement practice involves analyzing and reporting uncertainty, many reports unfortunately include a minimum of such information. Additionally, the large majority of measurements are not independently repeated, so statistical analysis is limited. CRC Handbook topic experts draw on their experience to make their judgments about the data quality and the associated uncertainty. The evaluation process takes time, but the results are important because the majority of chemical and physics data users are not experts in how measurements are made and need to rely on our experts to select the best measurement results.

The success of the CRC Handbook over its 100+ years is due to the quality and dedication of our authors and evaluators. As the number of chemical substances continues to explode and new topics in chemistry and physics grows, the Editors are constantly bringing in new evaluators who volunteer their time and expertise to ensure the CRC Handbook maintains its high quality and relevance to 21st Century science.

John Rumble

Editor-in-Chief

CRC Handbook of Chemistry and Physics

Gaithersburg, Maryland

January 2022

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The CRC Handbook of Chemistry and Physics (HBCP) contains over 700 tables in over 450 documents which may be divided into several pages, all categorised into 17 major subject areas. The search on this page works by searching the content of each page individually, much like any web search. This provides a challenge if you want to search for multiple terms and those terms exist on different pages, or if you use a synonym/abbreviation that does not exist in the document.

We use metadata to avoid some of these issues by including certain keywords invisibly behind each table. Whilst this approach works well in many situations, like any web search it relies in the terms you have entered existing in the document with the same spelling, abbreviation etc.

Since chemical compounds and their properties are immutable, a single centralised database has been created from all chemical compounds throughout HBCP. This database contains every chemical compound and over 20 of the most common physical properties collated from each of the >700 tables. What's more, the properties can be searched numerically, including range searching, and you can even search by drawing a chemical structure. A complete list of every document table in which the compound occurs is listed, and are hyperlinked to the relevant document table.

The 'Search Chemicals' page can be found by clicking the flask icon in the navigation bar at the top of this page. For more detailed information on how to use the chemical search, including adding properties, saving searches, exporting search results and more, click the help icon in to top right of this page, next to the welcome login message.

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