[davidsmith73]

Originally Posted by Chris Noble

If Sylvia Browne claims she is psychic then it is perfectly valid to test her specific claims. In the absence of a theory of "psi" what do you expect scientists to do? Test the infinite number of possible claims?

I expect scientists to apply their skills and knowledge to find out what is really going on. In the case of Jaytee, I don't think Wiseman et al. did a very good job of this. Although I'll give them the benefit of the doubt and suggest they ran out of time and resources...

If you read Sheldrake's first paper he was indeed claiming that the time that Jaytee began signalling was correlated to the time that Pam began the return journey.

In 20 cases Jaytee reacted at the time PS set off, or within 2 minutes of this time (Table 1).

Figure 2 shows a linear regression implying that the dog's behaviour really does have predictive power.

But it's entirely possible, and probable, that any predictive power such as this would be masked in an analysis where trials are classed as a failure because the dog goes to the waiting area for a few moments during the non-return period. Sheldrake may well have been looking at the temporal precision of this effect, but he was wise not to adopt Wiseman et al's criteria of 'hit' and 'miss' because that just massively increases your chances of type II errors for reasons I outlined before.

I would find these post hoc excuses more convincing if they were applied more uniformly. For instance in Wiseman's first trial the dog only spend 15 seconds at the window where there was no obvious reason during the return period. Sheldrake didn't seem to mind if the dog was responding to cars pulling up outside the house and dogs walking by if it happened to be during the return period.

In the case of Sheldrake, I'm sure he was aware of these issues before he ran his experiments, so these "excuses" are not likely to be post-hoc. If you're talking about post-hoc in the sense of explaining why Wiseman et al's data didn't show an effect, I would call it "criticism" rather than "excuses".

The best way would be not to exclude any data due to distractions because you run into huge difficulties deciding what is a distraction and what is not. The best way would be to analyse the data in such away that noise causd by distractions are kept to a minimum.

I'm not clear what you are saying here.

I'm suggesting a way to analyse the data using the amount of time in the waiting area as the dependent variable. If you simply calculate the proportion of time spent in the waiting area during return and non-return periods then will get the artifact you were talking about. If we consider the dog behaviour in our 100 min trial example we've been using, this would result in 100% waiting time during the return period and 90% for the non-period. I am suggesting that the waiting time is calculated as a proportion of the total time in the waiting area across return and non-return periods. This would give 10% for the return period and 90% for the non-return period (ie., 100 min of waiting in the waiting spot, 90min during non-return but only 10min during the return period). This would guard against the artifact you were talking about, I think.

I think the main point is that it is imperative to have criteria for judging the success or failure of a trial set up before they are undertaken. It is imperative that these criteria really test the claims that are being made. It is inexcusable that Sheldrake has not done this in all this time.

No, it's not imperative at all. Not many behavioural experiments measuring a continuous variable would adopt a 'hit' and 'miss' approach. It's more sensible to compare means of the dependent variable between conditions.

If Alex actually applies for the Randi 1 million dollar challenge he will have to do this.

Now, that I may have to agree with you on. But I'm sure it will on JREF's insistence.