unsure about response

dwen

New Member
#1
For the data set below, I want to fit a model for log seizure rate, including the main effect of treat and time (as categorical variable with 5 levels), and their interaction.

the response is "log seizure rate"
i'm not sure what exactly is it?
can anyone give a hand please?


****************************************************

Data on seizure counts for 59 epileptics.

Source: Table 2 (page 664) in Thall and Vail (1990).
With permission of Blackwell Publishing.

Reference: Thall, P.F. and Vail, S.C. (1990). Some covariance models for
longitudinal count data with overdispersion. Biometrics, 46, 657-671,


Description:

The data are from a placebo-controlled clinical trial of 59 epileptics.
Patients with partial seizures were enrolled in a randomized
clinical trial of the anti-epileptic drug, progabide. Participants
in the study were randomized to either progabide or a placebo, as
an adjuvant to the standard anti-epileptic chemotherapy. Progabide
is an anti-epileptic drug whose primary mechanism of action is to
enhance gamma-aminobutyric acid (GABA) content; GABA is the
primary inhibitory neurotransmitter in the brain.
Prior to receiving treatment, baseline data on the number of
epileptic seizures during the preceding 8-week interval were
recorded. Counts of epileptic seizures during 2-week intervals
before each of four successive post-randomization clinic visits
were recorded.


Variable List:

Patient ID, Treatment (0=Placebo, 1=Progabide), Age,
Baseline 8 week seizure count, First 2 week seizure count,
Second 2 week seizure count, Third 2 week seizure count,
Fourth 2 week seizure count.


1 0 31 11 5 3 3 3
2 0 30 11 3 5 3 3
3 0 25 6 2 4 0 5
4 0 36 8 4 4 1 4
5 0 22 66 7 18 9 21
6 0 29 27 5 2 8 7
7 0 31 12 6 4 0 2
8 0 36 52 40 20 23 12
9 0 37 23 5 6 6 5
10 0 28 10 14 13 6 0
.
.
.
 

Mean Joe

TS Contributor
#2
For the data set below, I want to fit a model for log seizure rate, including the main effect of treat and time (as categorical variable with 5 levels), and their interaction.

the response is "log seizure rate"
i'm not sure what exactly is it?
can anyone give a hand please?

Variable List:

Patient ID, Treatment (0=Placebo, 1=Progabide), Age,
Baseline 8 week seizure count, First 2 week seizure count,
Second 2 week seizure count, Third 2 week seizure count,
Fourth 2 week seizure count.


1 0 31 11 5 3 3 3
2 0 30 11 3 5 3 3
3 0 25 6 2 4 0 5
4 0 36 8 4 4 1 4
5 0 22 66 7 18 9 21
6 0 29 27 5 2 8 7
7 0 31 12 6 4 0 2
8 0 36 52 40 20 23 12
9 0 37 23 5 6 6 5
10 0 28 10 14 13 6 0
.
.
.
Ok, just giving a guess here. It looks like the 4th column is "Baseline 8 week seizure count", which is the number of seizures in 8 weeks? If so, then one seizure rate you can find is to divide this value by 8, to get the rate of seizures per week. Then you take the logarithm, and that would be a "log seizure rate".

You could alternatively calculate a rate of seizures per two-week period, using the last 4 columns.