DATE8 comparison

Compares dates in the format of YYYYMMDD by measuring the number of days difference between two dates. Weights are prorated according to the magnitude of the disagreement.

The DataStage® and QualityStage® date fields and character date fields with the date format of YYYYMMDD are supported.

Required Columns

The following data source and reference source columns are required:

  • Data. The date from the data source.

    You can use this comparison with vectors and reverse matching. If you want to create vectors to use in the Match Designer, see Make Vector stage in DataStage.

  • Reference. The date from the reference source (only applies for a two-source match).
Note: An invalid date is treated as a missing value.

Required Parameters

At least one of the following parameters are required:

  • Param 1. Indicates the maximum number of days difference that will be tolerated before the entire disagreement weight is assigned. If you specify a value for only the Param 1 parameter, this difference is the number of days that can be tolerated for either reference source date greater than data source date, or data source date greater than reference source date.
  • Param 2. (Optional) The maximum number of days difference that can be tolerated when reference source date is less than data source date.

Example

Suppose you are matching on birth date and specified a 1 for the Param 1 parameter. The full agreement weight is always assigned if no difference is found. If you specify 1 and the birth dates differ by one day, the weight assigned is calculated as follows: 
agreement weight - 1/2 (agreement weight + disagreement 
weight)

Two or more days difference results in the disagreement weight. The disagreement weight is always a negative number. Thus, one day difference would yield a partial weight.

If you specify 2, the errors are divided into thirds. One day difference results in assigning the agreement weight minus 1/3 the weight range from agreement to disagreement. Two days difference would receive the agreement weight minus 2/3 the weight range, and so on. Thus, the weights are prorated according to the seriousness of the disagreement.

Suppose you want to match highway crashes to hospital admissions. A hospital admission cannot occur before the accident date to be related to the accident. You might specify a 1 for the Param 1 parameter, which allows the admission date to be one day later (greater) than the crash date, and a 0 for the Param 2 parameter, which does not allow an admission date earlier than the crash date.