Readme for ALP Industry Level-to-Trademark (NICE Level) Crosswalk
When using the concordance, please cite the following paper:
Zolas, Nikolas J. and Travis J. Lybbert and Prantik 2013. “An ‘Algorithmic Links with Probabilities’
Concordance for Trademarks: For Disaggregated Analysis of Trademark & Economic Data.” CES
Working Paper 13-49 and WIPO Economic Research Working Paper 14.
Filenames
Each file name begins with the original industry classification or trademark class (i.e. “isic_rev2” or
“nice”) and level of aggregation(1-4). It is then separated by “_to_” and ends with the new industry or
trademark classification and level of aggregation.
List of Variables
Each file contains 3 variables: an industry classification variable, trademark classification variable (“nice”
and a weight. The first column of each file contains the original classification, while the second column
contains the new classification. The third column contains the probability weight of the original
classification to the new classification. The ALP concordance is constructed using probability weighting,
meaning that the weights provided for each industry level-patent level matching is between 0 and 1. All
weights by industry or technology class should also sum up to 1.
The classification system of the industries is given in the column heading. For the Standard Industrial
Trade Classification (SITC), we have Revisions 2, 3 and 4. For the International Standard Industry
Classification (ISIC) system, we have Revisions 2, 3, 3.1 and 4. For the North American Industry
Classification System (NAICS), we have the 1997, 2002 and 2007 Revisions. On the Trademark side, we
use the NICE Classification System (10th Edition – 2012).
Weighting
The weights provided are derived using the Hybrid probability weighting structure described in Lybbert
& Zolas (2014) and in the above paper.
Crosswalk Use
To use the crosswalk, simply multiply the value of the variable in the original classification by the
provided weights (Column 3). For instance, if one were to analyze the trademark flow for 2-digit SITC
Rev. 3 industries, one would simply multiply the trademarks by the weight found in Column 3 of
“nice_to_sitc_rev3_2.txt” to obtain new trademark quantities in SITC form.
Notes: Due to the probability weighting structure of the crosswalk, none of the crosswalks can be
inverted or worked backwards. For example, you cannot use the “sitc_rev3_2_to_nice.txt” file to
convert NICE into SITC Rev. 3. For this reason, we provide crosswalks working in both directions.
Levels of Aggregation
In addition to providing crosswalks both to and from NICE in order to ensure backward compatibility, we
provide crosswalks for different levels of aggregation (i.e. 1-4 digit levels of aggregation depending on
industry classification). The justification for doing this is similar to the reasoning for ensuring backward
compatibility. Industry classifications are given in a hierarchical structure. This hierarchy does not
assume that each level is weighed equally for the upper level, thereby requiring separate crosswalks for
each level of aggregation.
Layering of Additional Concordances
Suppose that the classification of the variables you start with or want to finish with differs from the
classifications provided. It is possible to layer additional concordances onto the original crosswalk.
However, doing so may introduce noise and thereby reduce the precision of the concordance. While this
should not be an issue in industries that have one-to-one correspondences, (such as many U.S. Standard
Industry Classifications (SIC) and NAICS), for industries with few one-to-one correspondences it may
pose a serious issue.
We will continue to update and provide additional industry classifications to the crosswalk and we
encourage feedback from users. If you would like to see an industry classification currently not provided
for in future editions of the crosswalk, please contact the authors with this request.
Nikolas Zolas
Nikolas.j.zolas@census.gov
Travis Lybbert
tlybbert@ucdavis.edu