Question

Groups of dolphins were systematically observed off the coast of Iceland near Keflavik in 1998. Each observation included the main activity of a dolphin group (Activity) and the time of day the group was observed (Time). The groups varied in size, with feeding or socialising groups usually including more dolphins than travelling groups, but no information about group size was included with the data. The observations are summarised in the following table: No. of groups, summarised by activity and time. Time Morning Noon or Afternoon Evening Activity Travelling 6 20 13 Feeding 28 4 56 Socialising 38 14 10

(a) In looking for an association between Activity and Time, which variable would be the predictor and which the response? Justify your answer.

(Is this correct),My answer is-

1. The predictor variable is the main activity of a dolphin group

         (Activity) and the response variable the time of day the group was

         observed (Time). The Activity of the dolphins decides what time of day

         it is.

(b) How strong is the evidence that dolphin activity typically varies during the day? Test at a 1% significance level.If you conclude that there is a relationship, describe it.

Does this look like I am on the right path?

(My answer)

1. H0: There is no association between Dolphin Activity and the Time of day.

H1: There is some association.

     Significance Level: α= 0.01

         The test requires for the sample to be randomly selected and all the

         expected observations to be ≥5.

(My question)-It says the dolphins are systematically observed(does that mean it is not a random sample?)

Answer 1