[tips] Sample Size: How to Determine it?

2013-08-27 Thread Michael Britt
I'm reading an interesting piece of research on anthropomorphism which essentially states after a natural disaster if we use the term mother nature when describing it, people will be less willing to contribute to relief efforts (Humanizing nature could help the perceiver to conceive natural

Re: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Paul C Bernhardt
There is software to determine this. One excellent and free app is G*Power. http://www.psycho.uni-duesseldorf.de/abteilungen/aap/gpower3/ I would use the correlational study to give me an estimate of effect size. As you describe, I would use that in the software to estimate my number of

RE: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Stuart McKelvie
Dear Tipsters, There are various ways to plan sample size. When teaching this in research methods, I divide the issues into two parts: 1. Estimation of population values. Here, more is better but there are diminishing returns. Think of the fact that we rarely see more than 1500 people in

Re: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Michael Britt
Thanks Paul. I've downloaded G*Power. Question: the correlational component of the study revealed r = -.21, p04 (higher tendency to humanize nature were associated with a lower tendency to help victims of a natural disaster). The next test will be an independent samples t-test. How does

RE: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Jim Clark
Hi A couple of observations to add to what others have said. First, note that the reported p (.06 or .0619, precisely) is for a non-directional test. If the authors predicted the difference, directional p is half of this (.031) and significant. This is consistent with the moderate or large

Re: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Ken Steele
Hi Michael: Be careful with the effect size statistic that G*Power uses, sometimes it is using rho. rho = .3 would be a medium effect size. Ken PS - It is surprising how underpowered are many of the experiments reported in the journals.

RE: [tips] Sample Size: How to Determine it?

2013-08-27 Thread rfro...@jbu.edu
I am assuming this was an independent samples t test where some participants heard the mother nature language and others didn't. Using the d of .53 they obtained as my estimate of what effect size they would be interested in obtaining (or that they think would be worthwhile to note), it appears

RE: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Mike Palij
I was going to stay out of this discussion but I have to address a couple of points, one of which is made by Rick at the end of his post: (1) The major problem with power analysis is that it requires one to have knowledge of POPULATION PARAMETERS, that is, the means, the standard deviation, the

[tips] Tenure Track Opening: Adult Clinical

2013-08-27 Thread Pollak, Edward (Retired)
West Chester University invites applications for a tenure-track faculty position in Clinical Psychology at the assistant professor level. Applicants must have a Ph.D. in psychology, an active program of research with an adult population, and the ability to mentor undergraduate and graduate

RE: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Wuensch, Karl L
My two cents: Decide on what is the smallest effect that you would consider to be of importance. If you think Type I and Type II errors are equally serious, then set both alpha and beta to .05, that is, find N for 95% power. G*Power does this with ease, but you are unlikely to like

[tips] noninvasive brain-to-brain interface in human beings

2013-08-27 Thread Carol DeVolder
Another interesting tidbit from Science Daily: http://www.sciencedaily.com/releases/2013/08/130827122713.htm -- Carol DeVolder, Ph.D. Professor of Psychology St. Ambrose University 518 West Locust Street Davenport, Iowa 52803 563-333-6482 --- You are currently subscribed to tips as:

Re: [tips] Sample Size: How to Determine it?

2013-08-27 Thread Paul C Bernhardt
It's hard to know what I would conclude. Are there other significant effects found in the study with the small sample size? Power is not an issue if you have statistical significance. I have a published paper in which one study has an N of 8, four in each of the two groups. It was significant

[tips] Belfast not Dublin,you dummy.

2013-08-27 Thread michael sylvester
On tonight's Jeopardy game the final question dealt with what area of Ireland are there distinctive markings indicating Protestant and Catholic neighborhoods.All three of the contestants wrote down Dublin.I wonder if they have heard of William of Orange. Btw,I hosted a college student from

Fw: [tips] Tenure Track Opening:

2013-08-27 Thread michael sylvester
Donald Trump University Please submit $4000 with youur application michael --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5n=Tl=tipso=27399 or send a blank email to