The Relationship Between Metrology Patents and Quality Infrastructure

As we continue our efforts to measure quality infrastructure (QI) development and improve QI data collection to understand QI’s contribution to economic growth, we turn our attention to metrology. We examined the relationship between the Global Quality Infrastructure Index (GQII) and the number of metrology patents filed to understand whether it would be a suitable proxy for metrology development. We expect a strong positive relationship between the variables of interest, suggesting that countries with higher metrological competencies will likely have more metrology patent applications.

The data on metrology patent filings was accessed from the European Patent Office (EPO) Worldwide Patent Statistical Database (PATSTAT), and the data on the GQII was accessed from the GQII database. We look at the sum of metrology patents filed by both the applicant and inventor countries for the period 2000-present.1 We examine this relationship using correlations2 as they allow us to assess patterns within data and determine whether any relationships that merit further exploration exist. The results of the correlations can be seen in Table 1.

Variables	Correlation Coefficient – Metrology Patent Filings – Applicant Country	Correlation Coefficient – Metrology Patent Filings – Inventor Country
Overall GQII score	0.3496***	0.3496***
GQII Metrology score	0.3988***	0.3989***
Number of domestic accredited calibration laboratories according to ISO 17025	0.6642***	0.6674***
Total number of key comparisons	0.6792***	0.6829***
Total number of supplementary comparisons	0.4672***	0.4721***
Total number of CMCs	0.6518***	0.6562***
Mass and Related Quantities	0.5782***	0.5822***
Electricity and Magnetism	0.5549***	0.5458***
Length	0.3693**	0.3666**
Time and Frequency	0.2373	0.2427
Thermometry	0.3297**	0.3304**
Photometry and Radiometry	0.4539**	0.4531**
Flow	0.7557***	0.7619***
Acoustics, Ultrasound, and Vibration	0.0013	0.0056
Chemistry	0.4996***	0.5107***

Table 1:  Correlation Results: Source: Own elaboration using data from the GQII and EPO-PATSTAT  Significance levels: p ≤ 0.05, *p ≤ 0.01, ***p ≤ 0.001.

First, we examined the relationship between metrology patent filings and the overall GQII score. The correlation coefficients indicate a positive and significant relationship, though moderate in magnitude. This suggests that while countries with higher GQII scores tend to have a higher number of metrology patents, some other factors are confounding the relationship. As expected, Figure 1 shows that the top 5 out of 185 countries in the GQII ranking (Germany, China, the USA, the UK and Japan) have the highest metrology patent filings. Also in line with our expectations are countries like Brazil (17), South Africa (20), Malaysia (33) and Colombia (39), which are in the top fifty of the GQII ranking and also have a high number of metrology patent filings. However, some outliers exist, with countries like Panama (99), Iceland (110) and Lichtenstein (164) ranking relatively low in the GQII while having a high number of metrology patent filings. Conversely, countries like Uzbekistan (67) and Ethiopia (83) are highly ranked in the GQII while having a very low number of metrology patent filings.

Figure 1: Metrology patent filings by GQII score: Source: Own elaboration using data from the GQII and EPO-PATSTAT 

Figure 2 shows the distribution of metrology patent filings for Germany, China and the USA from 2000-2021. Germany, which ranked first in the GQII with an overall score of 99.37% and a long legacy of QI development, has a moderately increasing number of metrology patent filings over the period of interest. In our dataset, Germany had the third-highest number of metrology patent filings, trailing behind the USA and Japan, respectively. China is ranked second in the GQII, with an overall score of 99.12%. While starting with a very low base of metrology patent filings, there was a significant jump from 2015 to 2020, resulting in China having the fourth-highest number of metrology patent filings in our dataset. The USA is ranked third in the GQII with an overall score of 98.85%. It has maintained a dominant lead in metrology patent filings, far surpassing other countries over the period of interest. However, this position may soon be challenged as China continues its upward trajectory.

Figure 2: Metrology Patent Filings for Germany, China and the USA – 2000-2021: Source: Own elaboration using data from the GQII and EPO-PATSTAT 

We then looked at the relationship between metrology patent filings and the sub-indicator for metrology in the GQII. Similarly, the correlation coefficient is positive, moderate, and statistically significant. 

We delved deeper into the sub-sub-indictors3 that comprise the metrology component of the GQII to see if there is a relationship between them and metrology patent filings. The correlation coefficient indicates a strong positive relationship between the number of accredited calibration laboratories according to ISO 17025 and metrology patent filings. The same can be said about the relationship between the total number of key comparisons a country participates in and metrology patent filings.  Similarly, a strong, positive relationship exists between the total number of Calibration and Measurement Capacities (CMCs) in a country and metrology patent filings. A closer look at the relationship between CMCs and metrology patent filings shows that the effects are stronger for the following metrology areas: Mass and Related Quantities, Electricity and Magnetism, and Flow. Moderate effects can also be seen for Length, Thermometry, Photometry and Radiometry, and Chemistry. The results were insignificant for Time and Frequency, and Acoustics, Ultrasound, and Vibration. Finally, a moderate positive relationship exists between the total number of supplementary comparisons a country participates in and metrology patent filings. All correlations are statistically significant at conventional levels.

The implications of these correlations suggest that other variables, particularly the number of accredited calibration laboratories according to ISO 17025, the number of key comparisons and the number of CMCs, may be better proxies for metrology development. However, accessing data on these proxies with a sufficiently long time series and at the level of granularity needed for more rigorous statistical analysis remains challenging. 

The Bureau International des Poids et Mesures (BIPM) collects data on CMCs, as well as on key and supplementary comparisons. However, only some of this data is accessible to the public on the BIPM’s Key Comparison Database (KCDB). For instance, it is only possible to download the most recent data on the total number of CMCs disaggregated by countries, metrology areas and regional metrology organizations (RMOs) (Ramkissoon and Harmes-Liedtke, 2024). However, this data is not broken down by year. Although not directly accessible to the public, time-series data appears to be available from 2000 to the present. Time-series data of CMCs can be downloaded for individual countries. Still, it must be done one country at a time, as there is no option to download this data for multiple countries simultaneously.   

Regarding key and supplementary comparisons, the data situation is similar. While the data is available from around 2000 to the present, it is not made accessible in a format that facilitates statistical analysis. It is possible to download recent data from the KCDB on the total number of key and supplementary comparisons disaggregated by metrology areas and RMOs (Ramkissoon and Harmes-Liedtke, 2024). In addition, aggregate data on the number of key and supplementary comparisons is available for each country, with the option to select multiple countries simultaneously. However, an annual breakdown of this data at the country level is not available. Although an annual breakdown of the data is possible, it aggregates all countries into a single total, thereby losing the granularity required for statistical analysis.

An even greater hurdle is accessing time-series data at the country level on the number of accredited calibration laboratories in accordance with ISO 17025. The GQII team collected this data by sending questionnaires to Accreditation Bodies (ABs) around the world. The completed questionnaires are then verified against the data published on the ABs’ websites. For ABs that do not respond, the GQII team relies on the data available on their websites. The entire process is time-consuming and labour-intensive, made more taxing by the significant variation in data presentation, accessibility, scope, and the frequency with which ABs update their websites. The International Laboratory Accreditation Cooperation (ILAC) collects data on the number of accredited calibration laboratories according to ISO 17025 for its annual report (Ramkissoon and Harmes-Liedtke, 2024). A time-series of at least fifteen years is available; however, this data is only presented in a graphic in the report and is not publicly available in a format that allows for statistical analysis. Furthermore, it is not clear whether the data collected by ILAC is disaggregated at the country level. Given this, we can only be certain that country-level data for this particular indicator is available for the years in which the GQII was collected.

In conclusion, while indicators such as the number of accredited calibration laboratories according to ISO 17025, the number of key comparisons and the number of CMCs may serve as stronger proxies for metrology development than the number of metrology patents filed, we are unable to further investigate these relationships due to the data limitations. Consequently, these data gaps hinder our ability to examine QI’s contribution to economic growth. Addressing these data limitations would enable a more robust exploration of QI’s role in economic development and support evidence-based policy and investment decisions for QI. 

Acknowledgements: 

We would like to express our gratitude to Dr Peter Neuhäusler (Fraunhofer Institute for Systems and Innovation Research ISI) for giving us access to the metrology patent data from the EPO Worldwide Patent Statistical Database and Dr Abhishek Saurav (The World Bank) for his support with this undertaking. 

References

Harmes-Liedtke, U. and Matteo, J.J. (2021) Global Quality Infrastructure Index Report 2020. Bad Homburg/ Germany and Buenos Aires/ Argentina.

Ramkissoon, A.-S. and Harmes-Liedtke, U. (2024) ‘The State of the Art in Quality Infrastructure Data’, in A. BHATNAGAR et al. (eds) Handbook of Quality System, Accreditation and Conformity Assessment. Singapore: Springer Nature.

1. Data from 2021 onwards may be incomplete due to the time-lag between the date national patent offices submit their data to the European Patent Office (EPO) and the date it is published.

2. The existence of a correlation does not imply causation. 

3. The metrology component of the GQII is comprised of six sub-indicators, some of which are comprised of various sub-sub-indicators (Harmes-Liedtke and Matteo, 2021). We look at three of the six sub-indicators of the metrology component in this analysis – the total number of key and supplementary comparisons, the number of accredited calibration laboratories ISO 17025 and the number of calibration and measurement capacities. We do not look at the sub-indicators related to memberships to the International Bureau of Weights and Measure, and various regional metrology organizations, and participation in consultative committees.