You are using survival analysis to project the population growth or decline for Boston over the next 10 years. The cohort period is five years. Which factor would introduce the most error into this calculation? Number of individuals surviving by cohort for each 5 year period No of families and legal partnerships between unrelated parties created for each 5 year period. Age of the mother giving birth to her second child for each 5 year period Number or births by cohort that occurred over each 5 year period Net migration that occurred for each 5 year period