Dear all,
I would like to look to use bootstrap to look at the difference between the ratio outcome of two groups (Ratio group 1 = 0.36 VS Ratio group 2 = 0.29).
See below my syntax for calculating the ratio for each group and the outcome of this syntax in my SPSS data file.
DATASET ACTIVATE DataSet1.
AGGREGATE
/OUTFILE=* MODE=ADDVARIABLES
/BREAK=Group
/MeanMeasurement=MEAN(Measurement).
AGGREGATE
/OUTFILE=* MODE=ADDVARIABLES
/BREAK=Group
/MeanResiduals =MEAN(Residuals).
COMPUTE Ratio=MeanMeasurement / MeanResiduals.
EXECUTE.
SPSS data file:
Subject Group Measurement Residuals MeanMeasurement MeanResiduals Ratio
1 1 3 15 3,92 10,75 0,36
1 1 4 10 3,92 10,75 0,36
1 1 3 11 3,92 10,75 0,36
2 1 4 9 3,92 10,75 0,36
2 1 4 7 3,92 10,75 0,36
2 1 3 10 3,92 10,75 0,36
3 1 4 12 3,92 10,75 0,36
3 1 5 13 3,92 10,75 0,36
3 1 4 9 3,92 10,75 0,36
4 1 5 9 3,92 10,75 0,36
4 1 4 11 3,92 10,75 0,36
4 1 4 13 3,92 10,75 0,36
5 2 1 7 2,22 7,78 0,29
5 2 2 6 2,22 7,78 0,29
5 2 2 9 2,22 7,78 0,29
6 2 3 8 2,22 7,78 0,29
6 2 2 9 2,22 7,78 0,29
6 2 2 8 2,22 7,78 0,29
7 2 3 7 2,22 7,78 0,29
7 2 3 7 2,22 7,78 0,29
7 2 2 9 2,22 7,78 0,29
Because the outcome of the syntax is just one value for each group (the ratio is an outcome of the mean of one variable divided by the mean of another) there is no distribution of the ratio in each group and so a statistic analysis to determine the statistical difference between these groups is not possible.
That’s why I thought about using bootstrapping. In this case I would request 1000 bootstrap samples and then perform my analyses (syntax) for each sample. My outcome would then consist of 1000 ratio’s (from the syntax analysis of 1000 samples) for each group and then I would be able to compare these median’s between the groups.
Am I right about this assumption? And is it possible to perform this kind of bootstrapping? Does anyone know how to perform this or how to write these steps in my syntax?
Thanks in advance!!
With kind regards,
JM
