Update Second Round Harmonisation - clarification of what to do if motor dictionary codes have changed

Second-Round-Harmonisation.md

@@ -42,7 +42,7 @@
  | Do you recommend a specific tool to calculate the requested z-scores for harmonization of birth weights, heights etc as batch? | No. The z-scores only need to be harmonised if they already exist in your data set and/or if there are country-specific norms that are in general usage (e.g. both UK and France have specific growth curves that have been created for their populations). |
  | Our follow-up sweep covers a period of several years (i.e. different ages). How do we handle this given that the variables specify outcomes at specific ages? |  We suggest that you assume the follow-up occurred at the *average age* of the follow-up - so for 2-3 years, you could use 2.5 years, or for 11-15 years you could use 13 years. Alternatively, you could work out the average age of the children that were seen, e.g. for 11-15 year sweep it may be that the majority of children were seen at 11 years, but a small percentage were difficult to find and only followed-up later on; in this case 11 or maybe 12 years could be a more appropriate age to use. Remember, also, that there variables (in the 'child_vital_status' dictionary) where the exact age of the child at the follow-up should be recorded, so it will be possible for people to use this information if required. |
  | Should we use chronological or corrected age? | Traditionally, correction for preterm birth was only carried out until 2 years of age, but this is starting to change. We recommend that you include whichever you have used for that particular follow-up sweep in the 'exact_age_dyrs_*' variables, and that you **make clear in the description of the data set whether data are based on chronological or corrected age.** |
- | The codes have changed for the motor dictionary variables, do I need to do anything? | If you have already harmonised these variables from your cohort and the codes were OK, you don't need to do anything as we have only removed codes that were conflicting (and so you would have run into difficulties previously) and added new ones. If you haven't yet harmonised your data, then you can just use the new version of the dictionary and there shouldn't be any problems. |
+ | The codes have changed for the motor dictionary variables, do I need to do anything? | _If you have already harmonised these variables from your cohort and the codes were OK, we recommend that you review the harmonisation_ although you shouldn't need to do anything extra as we only removed codes that were conflicting (you most likely would have run into difficulties previously) and added new ones; however, there is a small chance you may need to update the codes. If you haven't yet harmonised your data, then you can just use the new version of the dictionary and there shouldn't be any problems. |
  | The motor dictionary now contains the code `-99` for missing score data, do I need to do anything extra? | If you have already harmonised your data, you don't need to do anything new. However, If you have not yet harmonised your data, then using these new codes will help standardise across cohorts. |
 
 ### Data questions - subjects