Groups of dolphins were systematically observed off the coast of Iceland near Ke

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 Noon or Afternoon Evening Travelling 20 4 14 13 56 10 E Feeding 28 38 (a) In looking for an association between Activity and Time, which variable would be the Socialising predictor and which the response? Justify your answer. How strong is the evidence that dolphin activity typically varies during the day? Test ata 1% significance level. If you conclude that there is a relationship, describe it. (b)

Explanation / Answer

a) Time would be predictor

Response would be Activity

b)

TS = 65.06867

critical value = 13.2767

since TS> critical value

we reject the null hypothesis , and conclude that there is significant relationship between two variables

c1 c2 c3 sum r1 6 20 13 39 r2 28 4 56 88 r3 38 14 10 62 sum 72 38 79 189 Eij 1 2 3 expected 1 6 20 13 2 28 4 56 3 38 14 10 0i 6 20 13 28 4 56 38 14 10 Ei 14.85714 7.84127 16.30159 33.52381 17.69312 36.78307 23.61905 12.46561 25.91534 (Oi-Ei)^2/Ei 5.28022 18.85342 0.668676 0.910173 10.59743 10.03969 8.756144 0.188868 9.774062 sum 65.06867 critical value 9.487729

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