calculate_mean_linear_projection: no visible binding for global
  variable ‘id’
calculate_within_between_terms: no visible binding for global variable
  ‘id’
create_cohort: no visible binding for global variable ‘id’
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable ‘id’
calculate_within_between_terms: no visible binding for global variable
  ‘id’
create_cohort: no visible binding for global variable ‘id’
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable ‘id’
calculate_within_between_terms: no visible binding for global variable
  ‘id’
create_cohort: no visible binding for global variable ‘id’
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable ‘id’
calculate_within_between_terms: no visible binding for global variable
  ‘id’
create_cohort: no visible binding for global variable ‘id’
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable 'id'
calculate_within_between_terms: no visible binding for global variable
  'id'
create_cohort: no visible binding for global variable 'id'
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable ‘id’
calculate_within_between_terms: no visible binding for global variable
  ‘id’
create_cohort: no visible binding for global variable ‘id’
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable ‘id’
calculate_within_between_terms: no visible binding for global variable
  ‘id’
create_cohort: no visible binding for global variable ‘id’
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable 'id'
calculate_within_between_terms: no visible binding for global variable
  'id'
create_cohort: no visible binding for global variable 'id'
Undefined global functions or variables:
  id
calculate_mean_linear_projection: no visible binding for global
  variable 'id'
calculate_within_between_terms: no visible binding for global variable
  'id'
create_cohort: no visible binding for global variable 'id'
Undefined global functions or variables:
  id