ALGAE Protocol: Later life exposures, comparing uncleaned mobility vs life stage mobility assessments

An automated protocol for assigning early life exposures to longitudinal cohort studies

ALGAE Protocol: Later life exposures, comparing uncleaned mobility vs life stage mobility assessments (algae4900 - algae4916)

by Kevin Garwood

Context of Variables

These variables compare later life exposures generated by the uncleaned mobility assessment and life stage mobility assessment methods. Percent error values for cumulative, average and median exposure values are calculated for each pollutant (NAME, NOX_rd, PM10_rd, PM10_gr, PM10_tot) for each life stage (T1, T2, T3, EL) for each person.

The formula used to calculate percent error is: 

percent_error = (|approximate - exact| / exact) x 100

For these variables, ALGAE uses the cleaned mobility assessment to provide exact values and the life stage mobility assessment to provide approximate values. The formula becomes: 

percent_error = (|life stage mobility value - uncleaned mobility value| / uncleaned mobility value) x 100

See Calculations and Algorithms to find out more about percent error calculations.

Location of Result File

You will find these variables in a file having a name that fits the form: 
res_later_mob_uncln_vs_stg_mob_[Date stamp].csv
which will be found in the directory: 
later_life/results/exposure_data/method_comparisons

Example Result File

See here.

Variable Naming Conventions

It may be quicker to understand the variables through naming conventions rather than looking at specific table entries. The basic format of variables in this section follows this pattern: 
	algae49[0-16]_[pollution type]_[aggregate value]_percent_err

In this pattern:

  • algae49: indicates that they refer to comparing exposures that compare results between the uncleaned mobility assessment and life stage mobility assessments.
  • pollution_type: will be name, nox_rd, pm10_tot, pm10_rd, pm10_gr
  • aggregate value: sum for cumulative value, avg for average value and med for median value.

The pollutant codes have the following meanings:

  • name: high level pollution that comes from outside the exposure area
  • nox_rd: Nitrogen oxide pollution coming from roads
  • pm10_rd: PM10 particulate matter coming from roads.
  • pm10_gr: PM10 particulate matter coming from sources other than roads.
  • pm10_tot: PM10 particulate matter coming from either roads or other sources.

Variable Dictionary

Variable Description
algae4900_person_id An anonymised or pseudonymised identifier which represents a study member. ALGAE uses this variable to link data together for a given study member.
algae4901_life_stage The name of a life stage. For example, "T1" may be the name of the Trimester 1 life stage.
algae4902_name_sum_percent_err The percent error for cumulative NAME exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4903_name_avg_percent_err The percent error for average NAME exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4904_name_med_percent_err The percent error for median NAME exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4905_nox_rd_sum_percent_err The percent error for cumulative NOX_rd exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4906_nox_rd_avg_percent_err The percent error for average NOX_rd exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4907_nox_rd_med_percent_err The percent error for median NOX_rd exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4908_pm10_gr_sum_percent_err The percent error for cumulative PM10_gr exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4909_pm10_gr_avg_percent_err The percent error for average PM10_gr exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4910_pm10_gr_med_percent_err The percent error for median PM10_gr exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4911_pm10_rd_sum_percent_err The percent error for cumulative PM10_rd exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4912_pm10_rd_avg_percent_err The percent error for average PM10_rd exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4913_pm10_rd_med_percent_err The percent error for median PM10_rd exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4914_pm10_tot_sum_percent_err The percent error for cumulative PM10_tot exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4915_pm10_tot_avg_percent_err The percent error for average PM10_tot exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.
algae4916_pm10_tot_med_diff The percent error for median PM10_tot exposure. The uncleaned mobility assessment provides the exact value and the life stage mobility assessment provides the approximate value.