An Evaluation of Ad Hoc Presence-Only Data in Explaining Patterns of Distribution: Cetacean Sightings from Whale-Watching Vessels

Table 2

Factors present in the stepwise-reduced model for each dataset where significant multiple linear regressions were obtained. P indicates that the factor was present in the reduced model, and + or − indicates whether there was a positive or negative relationship of the factor compared to the number of Cetaceans. Where no + or − is present, the factor was a category variable. N/A indicates that this variable was not used as an explanatory factor in the analysis.

Factor	Full dataSet	Presence only	Presence only and behaviour
Date	P+
Boat	P
Time of day
Behaviour of cetacean	N/A	N/A	P
Presence of humpback whales
Presence of killer whale
Presence of white-beaked dolphin
Sea state		P−
Percentage of cloud cover	P+
Weather conditions
Wind direction
Tidal conditions
Swell height
Visibility	P+	P+
Sea surface temperature	P−		P−
Observer