I am running a metaanalysis about the age of girls and boys at the beginning of puberty (Tanner-stages) and it would be great if someone could help me out with two questions about significance tests for mean/median value differences.

question 1:

In SPSS I have the data of the results of about 50 empirical studies. The two relevant variables are:

A) Birth year of the girls of the study either in the range "1975 to 1989" or in the range "1990 to 2003", so this variable is dichotomous.

There are 16 older studies ("1975 to 1989") and 34 newer studies ("1990 to 2003").

B) age at which 50% of the girls of the study reach puberty (Tanner-stage 2). These values (when girls reach puberty) are in the real world normally distributed.

Let's say the 16 older studies show a mean age of 10,7 years for the beginning of puberty (reaching Tanner-stage 2) and the 34 newer studies 9,9 years.

How can I find out if this mean value difference is significant, which test is appropriate?

question 2:

Let's say the old studies show a MEDIAN age of 10,7 years for the beginning of puberty (reaching Tanner-stage 2) and the new studies 9,9 years.

How can I find out if this MEDIAN value difference is significant, which test is appropriate?

It would be really GREAT if someone could help me. Thank you very much in advance!

Best wishes

Filip