I have microarray z scores for gene set enriched (GSE) pathways that range approximately from -3 to 14. I understand that an absolute value of 1.96 has a p-value = .05 and significant for our purposes. My question is whether I can consider extreme z scores as more significant?
This is a statistical question. What a higher z value means is that it is more extreme (if you assume a normal distribution), thus a more extreme value is less likely to happen by chance. Which is translated to a (lower) p-value.
What it is significant and not is arbitrary. Prior to the experiment you must decide which is your threshold, how much chance you allow. Apparently you decided to select 0.05 as your threshold, which means that one of 20 results might be due to chance. But your extreme z score is not more significant, it is less expected (under the null hypothesis, those p-values might change if you change your null hypothesis, ie you think your genes expression don't follow a normal distribution) but as significant as your 0.0499999 p-values.