Is there a way to do meta-analysis for crossed designs (no control group)? I have a 2x2 factorial with count data that I would be interested in looking at. I basically did the same experiment five times and would like to look at the results across all five experiments simultaneously. Meta-analysis strikes me as the best option, but I've only done it to compare two groups before.
Further details on the study design if you are interested:
Factor 1: Soil type (two levels, organic or conventional)
Factor 2: Seed type (two levels, transgenic or not)
Soil used was from 5 different pairs of soil samples from organic and conventional fields and the experiment was run once for each pair. Or, to clarify:
Exp 1: Field 1 vs. Field 2
Exp 2: Field 3 vs. Field 4
Exp 3: Field 5 vs. Field 6
Exp 4: Field 7 vs. Field 8
Exp 5: Field 9 vs. Field 10
Where the odd numbered field is conventional and the even numbered field is organic each time.
Is meta-analysis the best way to combine results from these experiments? Is there another way? If meta-analysis is the best way, how do I go about doing it with four groups and no control?