Re: Stats question

[Christopher Lovelace]

Don, I'm no stats guru, but I'll throw this out as a way to characterize the bird's behavior with respect to probability: It seems to me that "chance" in this situation would be defined by the bird's normal feeding behavior. So, if you know how often (before your manipulation) it goes to the right first, then you could use the binomial distribution to figure out the probability of getting a certain number of "right" responses. So, considering the first repetition on each day, assuming that the bird's normal behavior is to go to the left first 95% of the time (and assuming each trial is independent, and that the probability of going left doesn't change, which is essentially the null hypothesis), the probability of getting zero "right" responses in the first 7 trials is about 1.0. The probability of getting four "right" responses in the last 7 trials is about 0.0002. This suggests to me that either this was a very, very unusual set of trials, or that the bird is now more likely to go to the right first (i.e., your manipulation worked). Cheers, Chris Lovelace --� Christopher T. Lovelace, PhD Assistant Professor Department of Psychology, University of Missouri - Kansas City 4825 Troost, Room 111-F, Kansas City, MO 64110 Voice: (816) 235-1067, Fax: (816) 235-1062 E-mail: [EMAIL PROTECTED] http://iml.umkc.edu/psyc/faculty/lovelace/ On May 26, 2005, at 3:18 PM, Don Allen wrote: Hi Tipsters- I need some advice on the best statistic to use. I'm doing some work that's outside of my normal area. I'm collaborating with a colleague in the Biology department and we're investigating learning in Raptors. In particular, red-tailed hawks. So far we have preliminary data on only one bird. The initial paradigm is to see if we can get the bird to shift its natural preference from feeding on the left side of the cage to the right side. First, food was available on both sides, then less food was available on the left and more was on the right. Finally, the bird only found food on the right. The bird's behaviour was as follows: -- Date� � � � Side first chosen May� � � 6� � � � L � � 7� � � � L � � 8� � � � L � � 9� � � � L � � 10� � � � L � � 11� � � � L, L (two trials) � � 12� � � � L, L B)� One piece under L cup, three pieces under R cup. May� � 13� � � � L, L � � 14� � � � L, L � � 15� � � � L, L � � 16� � � � L, L C) No food under L cup, four pieces under R cup. May� � 17� � � � L, L � � 18� � � � L, L � � 19� � � � L, L � � 20� � � � R, R � � 21� � � � R, L, R (three trials) � � 22� � � � R, R � � 23� � � � R, R, R My question is which is the best statistic to use to show that this shift in behaviour is beyond chance (alpha = .05) I seem to recall a program that calculated odds in an ABAB design, but I can't seem to find it in the Digest. Of course a simple conjoint probability calculation shows that the odds of six rights in a row is well below .05 but is there a better test to use? As usual, thanks in advance for your help. -Don Don Allen Langara College --� --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED] --- You are currently subscribed to tips as: archive@jab.org To unsubscribe send a blank email to [EMAIL PROTECTED]