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Data Collection
Five main data sources were used for the analysis:
- invasiveness and impacts criteria questionnaire (appendix 6). This questionnaire consisted of eleven questions, five on invasiveness and six on impacts. The questionnaire was provided to the three reference panels. Each panel member rated each weed against a six-point scale (seven points if the "don’t know" category is included);
- observed distribution and density for each weed based on 0.5 degree cells for Western Australia, New South Wales, Queensland, South Australia and the Northern Territory, 0.25 degree cells for Victoria and 0.125 degree cells for Tasmania and the Australian Capital Territory. Where States or Territories did not provide data, the distribution was taken from Parsons and Cuthbertson (1992) and other sources. These data were also used to calculate potential distributions of weeds and the number of IBRA regions affected;
- economic information on the current annual cost of control for agricultural and forestry weeds was provided by State and Territory agencies;
- environmental information on the number of threatened species and communities was provided by State and Territory agencies, and the monoculture potential of a weed by the reference panels; and
- a qualitative assessment by the reference panels of positive and negative social values caused by a weed (for impacts not included under other data sources).
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