Case study 10: Impact assessment of the effect of tsetse control on livestock productivity

Data management

Step 1. The table shows the years used for calculation of mean values for each variable. The study commenced in March 1986 but it took a little time for data collection to reach the desired level of quality.

This is an important point to remember when commencing a new field study with participating farmers. Often it takes a little while for the system for data collection to settle down.

Sometimes it is worth organising a preliminary, pre-study period of data collection to iron out any problems before the main study begins.

Note that calf body weights were calculated at 12-months of age for all calves that survived to 12 months. The table shows that calves born during 1998 could not be used for this calculation as these calves would not have reached 12 months of age until the following year which was beyond the end of the study. Similar reasoning applies to the calculation of calf mortality.

Year	Adult productivity	Adult mortality	Calf growth, body weight	Calf mortality	Abortions, calf/cow ratio	Herd size
1986	r	r	r	r	r	r
1987	a	a	a	a	a	a
1988	a	a	a	a	a	a
1989	a	a	a	a	a	a
1990	a	a	a	a	a	a
1991	a	a	a	a	a	a
1992	a	a	a	a	a	a
1993	a	a	a	a	a	a
1994	a	a	a	a	a	a
1995	a	a	a	a	a	a
1996	a	a	a	a	a	a
1997	a	a	a	a	a	a
1998	a	a	r	r	a	a