Study Number 8131 - International Study of Asthma and Allergies in Childhood, 1992-2005


Data Archive Processing Standards

The data were processed to the UK Data Archive's A standard. A rigorous and comprehensive series of checks was carried out to ensure the quality of the data and documentation.�Firstly, checks were made that the number of cases and variables matched the depositor's records. Secondly, checks were made that all variables had variable labels and all nominal (categorical) variables had value labels. Where possible, either with reference to the documentation and/or in communication with the depositor, absent labels were created. Thirdly, logical checks were performed to ensure that nominal (categorical) variables had values within the range defined (either by value labels or in the depositor's documentation). Lastly, any data or documentation that breached confidentiality rules were altered or suppressed to preserve anonymity.

All notable and/or outstanding problems discovered are detailed under the 'Data and documentation problems' heading below.

Data and documentation problems

Nothing encountered.

Useful Notes

Data file isaac2_10_11_individual_data
The data have been coded according to the 'ISAAC 2 Codebook for Analysis' document.
However, some variables cevering detectability of allergens, e.g. SD17, SD23, SD25, SD27, SD29 and SD33, have values of '-1', where only labels for '1' and '0' are given in the codebook.
flag_age - uncoded value '7' not included in codebook.
WB_S, AM_S, RM_S, EM_S include unlabelled codes of '40' not included in codebook.

Data file isaac3_6_7_env_ques_data
hgtunit - unlabelled values of 4.

Data conversion information

From January 2003 onwards, almost all data conversions have been performed using software developed by the UK Data Archive. This enables standardisation of the conversion methods and ensures optimal data quality. In addition to its own data processing/conversion code, this software uses the SPSS and StatTransfer command processors to perform certain format translations. Although data conversion is automated, all data files are also subject to visual inspection by a member of the Archive�s Data Services team.

With some format conversions, data, and more especially internal metadata (i.e. variable labels, value labels, missing value definitions, data type information), will inevitably be lost or truncated owing to the differential limits of the proprietary formats. A UK Data Archive Data Dictionary file (generally in Rich Text Format (RTF)) is usually provided for each data file, enabling viewing and searching of the internal metadata as it existed in the originating format. These files are called: [data file name]_UKDA_Data_Dictionary.rtf

Important information about the data format supplied

The links below provide important information about the Archive's data supply formats. Some of this information is specific to the ingest format of the data, i.e. the format in which the Archive received the data from the depositor. The ingest format for this study was Delimited text

Please follow the appropriate link below to see information on your chosen supply (download) format.

SPSS (*.sav)

STATA (*.dta)
Tab-delimited text (*.tab)
MS Excel (*.xls/*.xslx)
SAS (*.sas7bdat and *.sas)
MS Access (*.mdb/*.mdbx)

Conversion of documentation formats

The documentation supplied with Archive studies is usually converted to Adobe Portable Document Format (PDF), with documents bookmarked to aid navigation. The vast majority of PDF files are generated from MS Word, RTF, Excel or plain text (.txt) source files, though PDF documentation for older studies in the collection may have been created from scanned paper documents. Occasionally, some documentation cannot be usefully converted to PDF (e.g. MS Excel files with wide worksheets) and this is usually supplied in the original or a more appropriate format.