I am completely new to meta-analyses . My objective was to see how the date of planting of any specific crop affects the grain yield. While going through literature, we can find several literature based on different planting date but the important thing they don’t have any specific control (planting date). In addition, it is very hard to find the specific effect size for different planting date. Only thing we have mean yield. In this situation I would be glad if some one suggest the guidelines to perform meta analysis.