Data management

The basic data that we shall use to address the two questions defined under Questions to be addressed are stored in CS6Data1.

We first need to check the raw data (in Raw data worksheet of CS6Data1) to make sure that all the data are suitable for the analyses required. It will be important in particular to make sure that there has been regular milk recording for each cow and that no long gaps have occurred, especially in early lactation.

When scanning columns of data by eye it is sometimes helpful to first unstack the data. Here we unstack the column for the variable day using Spread → Manipulate → Unstack...(see dialog box below), so that the values for each cow can be read in a different column. Immediately we see that there is a long gap, for instance, between days of lactation 115 and 197 for cow 24 (headed 'day_24' in the spreadsheet below).