Hello - I am working through a university statistics course without prior knowledge of statistics, so I apologize if the description of my question is a bit basic:

I have a data set that includes the number of births by month for a 20 year period. The variables are 'year,' 'birthmonth,' and 'numberofbirths' (for that month). The measure for the 'year' and 'numberofbirths' is scale; the measure for 'birthmonth' is nominal.

I am required to use SPSS to determine the total number of births for each year. The first thing I did was sort my data so that all of the years display their months chronologically. I believe I need to go to Transform > Compute Variable > ... to determine the sum of births for each year. But I cannot figure out how to enter the computation in the numeric expression field.

Apologies for such a basic question. I have a math disorder, so simple calculations do not come easily to me.

Thank you for any information or guidance.