your assistance, please

[Helga Walz]

 

To the experts,

 

To determine differences between conditions such as the following, what
statistical procedure

would be most appropriate -

 

The 2 conditions for the I.V. are (C+I) and (I only) with pre and post
tests.  If some subjects who are giving the pretest

decide not to participate in condition 1 or 2, I would like to put them
into a static or control group.

 

Would it be appropriate to use a Repeat Measures Mixed ANOVA procedure?

One I.V. is (C+I) and (I only) and the second I.V. is the time - i.e.
from pre to post?

 

Would the same statistical method be appropriate if I randomly assign
the 3 conditions

(C+I) and (I only) and (control/static) conditions to a specific
location?

 

Thank you so much for your assistance,

 

Helga Walz

 

 

 

Helga S. Walz, Ph.D.

Division of Applied Behavioral Sciences

University of Baltimore

1420 North Charles Street

Baltimore, Maryland  21201

 

Tel.: [phone]

Fax.:[phone]

 

[statisticsdoc]

Stephen Brand
www.statisticsdoc.com

Helga,

Your design appears to be a Repeated Measures ANOVA, with three levels of
the between-subject factor (C+I, I only, No Treatment) and two levels of the
within-subject time factor.  It would have concerns about letting subjects
self-select into the static control group.  If you can, you want to start
with a group of subjects who are willing to participate in the treatments
and randomly assign some to a static control group (perhaps a waiting list
control group, if the treatment is something of benefit to the
participants).  Letting subjects self-select out of the treatments means
that the groups do not consist of comparable groups of randomly selected
individuals.  The inferences that you can draw are weaker: to what extent
does the control group differ because of treatment effects or
self-selection?

HTH,

Stephen Brand


For personalized and professional consultation in statistics and research
design, visit
www.statisticsdoc.com


-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]]On Behalf Of
Helga Walz
Sent: Friday, November 17, 2006 8:39 PM
To: [hidden email]
Subject: your assistance, please




To the experts,



To determine differences between conditions such as the following, what
statistical procedure

would be most appropriate -



The 2 conditions for the I.V. are (C+I) and (I only) with pre and post
tests.  If some subjects who are giving the pretest

decide not to participate in condition 1 or 2, I would like to put them
into a static or control group.



Would it be appropriate to use a Repeat Measures Mixed ANOVA procedure?

One I.V. is (C+I) and (I only) and the second I.V. is the time - i.e.
from pre to post?



Would the same statistical method be appropriate if I randomly assign
the 3 conditions

(C+I) and (I only) and (control/static) conditions to a specific
location?



Thank you so much for your assistance,



Helga Walz







Helga S. Walz, Ph.D.

Division of Applied Behavioral Sciences

University of Baltimore

1420 North Charles Street

Baltimore, Maryland  21201



Tel.: [phone]

Fax.:[phone]