Hi. I'm trying to understand what is a data set compliant with ISO 14044.

Is the reference guide referring to item 4.2.3.6 "Data quality requirements"?

4.2.3.6.1 Data quality requirements shall be specified to enable the goal and scope of the LCA to be met.
4.2.3.6.2 The data quality requirements should address the following:
a) time-related coverage: age of data and the minimum length of time over which data should be collected;
b) geographical coverage: geographical area from which data for unit processes should be collected to satisfy the goal of the study;
c) technology coverage: specific technology or technology mix;
d) precision: measure of the variability of the data values for each data expressed (e.g. variance);
e) completeness: percentage of flow that is measured or estimated;
f) representativeness: qualitative assessment of the degree to which the data set reflects the true population of interest (i.e. geographical coverage, time period and technology coverage);
g) consistency: qualitative assessment of whether the study methodology is applied uniformly to the various components of the analysis;
h) reproducibility: qualitative assessment of the extent to which information about the methodology and data values would allow an independent practitioner to reproduce the results reported in the study;
i) sources of the data;
j) uncertainty of the information (e.g. data, models and assumptions).

Where a study is intended to be used in comparative assertions intended to be disclosed to the public, the data quality requirements stated in a) to j) above shall be addressed.
4.2.3.6.3 The treatment of missing data shall be documented. For each unit process and for each reporting location where missing data are identified, the treatment of the missing data and data gaps should result In
— a "non-zero" data value that is explained,
— a "zero" data value if explained, or
— a calculated value based on the reported values from unit processes employing similar technology.
Data quality should be characterized by both quantitative and qualitative aspects as well as by the methods used to collect and integrate those data.
Data from specific sites or representative averages should be used for those unit processes that contribute the majority of the mass and energy flows in the systems being studied, as determined in the sensitivity analysis performed in 4.3.3.4. Where possible, data from specific sites should also be used for unit processes that are considered to have environmentally relevant inputs and outputs.