Data Quality and Sources
This appendix reports essential information on organizations, attacks, and public opinion. Readers should be aware that the quality of basic information is quite poor, and should therefore be very cautious about accepting as 'data' empirical evidence that is quite dubious and controversial (obviously, caution should also be used with our data, despite my efforts to avoid inaccuracies and mistakes).
The following six main issues should be borne in mind.
Internet style. A considerable amount of literature and information on the Arabic-Palestinian conflict can be found on the Internet. It suffers from the shabby and imprecise styles of many papers published on the Internet. The sources of information are often omitted or stated imprecisely. This often makes it impossible to know whether two coherent pieces of information are independent of each other. In fact, authors quite frequently reproduce parts of essays or articles published by others in an uncritical manner, thus propagating errors.
Conflicts between sources. Both data on SMs and data on public opinion are often inconsistent. The same episode is often described in totally diferent ways in the main databases: dates, death and injured counts, and organizations can differ according to source.a The same is true of surveys. The two principal sources of information on Palestinian public opinion are the Palestinian Center for Policy and Survey Research (PSR; CPSR up to 2001) and the Jerusalem Media and Communication Center (JMCC), which, however, often supply contradictory data: in the case of voting preferences, for example, Islamic organizations obtain greater support in the JMCC sample, while nationalist support is greater in the PSR sample.
a This is true, quite surprisingly, also for very famous episodes that were in the news at that
time, and in some cases are already included in history texts. See, for example, the attack on Lod
airport in 1972: date, number of casualties, and number of wounded vary considerably depend-
ing on the sources.