Losses in production of livestock products on farms due to diseases 
and other causes are expressed in terms of quantity and value obtained 
by the procedure described for crops. However, the acreage equivalent 
of lost value for individual diseases was not computed and only a 
consolidated estimate of the acreage equivalent of livestock losses 
is made. 
Some losses have not been expressed in terms of annual production lost. 
For example, reductions in productivity of land and other physical 
Capital due to erosion and other types of soil deterioration are ex- 
pressed as annual average quantities and value of resources lost, 
How Estimates Were Obtained 
Estimates of losses are based on statistical surveys and records 
wherever possible. However, they were not available for many causes, 
and it has been necessary to rely upon judgment estimates made by 
specialists in the different natural science fields. But even the in= 
formation that these specialists have available is limited; consequently, 
the accuracy or reliability of the estimates differs greatly. 
Each member of the committee served as a leader of a group within his 
agency, which assembled the estimates obtained from specialists. Most 
of the estimates were made in such a way as to be applicable to national 
data on production and resources. About 750 individual loss reports on 
separate commodities and due to separate causes of loss were prepared by 
about 100 specialists in the Department, and they were assembled and 
grouped according to causes and kinds of production affected. 
Adding estimates of losses from different causes affecting the same 
product in such a way as to avoid duplication or overestimating presented 
a special problem. It was assumed that percentage loss estimates could 
be added when they were low and from closely related causes, such as 
diseases affecting the same crop. However, it was frequently necessary 
to combine estimates from several different causes affecting the same 
product into a single estimate. This was done in consultation with the 
specialists who submitted the original estimates and the consolidated 
totals are considered conservative. 
The Agricultural Estimates Division of the Agricultural Marketing Ser- 
vice supplied data on national acreage, quantity of production, farm 
value of production, and other basic data against which loss estimates 
were applied to obtain national estimates. This Division also performed 
most of the computations necessary in summarizing estimates and made 
certain checks to see that estimates were mathematically consistent. 
Meaning of Estimates 
In interpreting estimates of losses shown in this report, it is essen- 
tial to recognize the assumptions on which they are based. 
