ALGAE Data Dictionary: Early life exposures, using cleaned mobility assessment

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

ALGAE Data Dictionary: Early life exposures, using cleaned mobility assessment (algae3100-algae3157)

by Kevin Garwood

Context of Variables

These early life exposure values are based on the cleaned mobility assessment method. It includes days that may have been involved in gaps and overlaps that appeared in the original address period file. Note that this method of assessment is different than the uncleaned mobility assessment, which ignores any gap or overlap in its calculations. For each study member, cumulative, average and median exposures are assessed based on two factors:

For each life stage, the protocol counts the number of days which can be described by the following categories for data quality:

Please see the Assess the Data Quality of Each Daily Exposure Value section of the ALGAE methodology to learn more about these data quality categories.

Variables marked _err aggregate daily exposure errors for a given pollutant and life stage.

Exposure Measurement Error Variables

The table also includes exposure measurement error variables that correspond with each aggregated exposure value. Exposure measurement errors are based on exposures that come from "days of contention". A day of contention is caused by a gap or an overlap in the residential history records, when a person could have occupied more than one location.

The exposure measurement error for a given day of contention is an opportunity cost, measured as the absolute difference between assigned and opportunity geocodes (See Calculations and Algorithms). The assigned geocode is one that the cleaning algorithm has assigned in its attempts to fix a gap or overlap. The opportunity geocode is the other location a person could have occupied on that day. If a day is not covered by a gap or overlap problem, then it will have a daily exposure error of zero.

Daily exposure error values are aggregated to match the context of the aggregated exposure values. If your address periods all have temporally contiguous start and end dates, then you should expect the exposure values to be zero.

You may observe that some of the exposure error values are not zero, but are extremely small values. We believe that some of these may owe to numerical round-off error and we advise that you decide on a threshold for assigning them zero.

Location of Result File

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

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. Most of the variable names fit one of the following patterns: ll variables in this section start with algae31, which indicates that the variables relate to the early life exposure assessment. This assessment makes full use of cleaned address periods and considers error values.

Variables related to exposure values will be of the format: 
	algae31[nn]_[pollution type]_[aggregate value]
	algae31[nn]_[pollution type]_err_[aggregate value]
	algae31[nn]_[pollution_type]_[daily exposure quality]_days

In these patterns:

  • nn: a two digit number.
  • pollution type: will be name, nox_rd, pm10_tot, pm10_rd, pm10_gr.
  • aggregate value: refers to one of sum, average or median operations that are applied to daily exposure values for a given life stage. They are represented by _sum, _avg and _med respectively.
  • err: means the value is an aggregation of daily error values measured for a given life stage
  • daily exposure quality: are variables that measure the number of days in a given life stage which exhibit different types of quality for exposures. The daily exposure data quality indicators are variables that cover categories such as good exposure days, invalid address days and out of bounds exposure days.

Be aware that in many cases field values with _err_ can be very small. Extremely small values can indicate either that the amount of error is small, or reflect numerical roundoff error somewhere in the calculations.

Variable Dictionary

Variable Description
algae3100_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.
algae3101_life_stage The name of a life stage. For example, "T1" may be the name of the Trimester 1 life stage.
algae3102_life_stage_duration The number of days in the life stage.
algae3103_name_inv_addr_days The number of NAME exposure days in the life stage that the study member spent at an invalid address. See definition of Invalid address days.
algae3104_name_oob_days The number of NAME exposure days in the life stage that the study member spent living at a location that is considered outside the bounds of the exposure area. See definition of Out of bounds days.
algae3105_name_poor_addr_days The number of NAME exposure days in the life stage that the study member spent living at a location whose geocode was derived from a poor quality residential address. The geocode was used to generate exposure values, but it is still considered to be invalid because it is of such poor quality. See definition of Poor address days.
algae3106_name_missing_exp_days The number of NAME exposure days in the life stage that the study member spent living at a valid geocode which has some exposure values but not for specific days. See definition of Missing exposure days.
algae3107_name_good_addr_days The number of NAME exposure days in the life stage that the study member spent living at a geocode that is considered a good match: it has a valid geocode and it has a non-blank exposure value for a given day. See definition of Good address days.
algae3108_nox_rd_inv_addr_days The number of NOX RD exposure days in the life stage that the study member spent at an invalid address. See definition of Invalid address days.
algae3109_nox_rd_oob_days The number of NOX RD exposure days in the life stage that the study member spent living at a location that is considered outside the bounds of the exposure area. See definition of Out of bounds days.
algae3110_nox_rd_poor_addr_days The number of NOX RD exposure days in the life stage that the study member spent living at a location whose geocode was derived from a poor quality residential address. The geocode was used to generate exposure values, but it is still considered to be invalid because it is of such poor quality. See definition of Poor address days.
algae3111_nox_rd_missing_exp_days The number of NOX RD exposure days in the life stage that the study member spent living at a valid geocode which has some exposure values but not for specific days. See definition of Missing exposure days.
algae3112_nox_rd_good_addr_days The number of NOX RD exposure days in the life stage that the study member spent living at a geocode that is considered a good match: it has a valid geocode and it has a non-blank exposure value for a given day. See definition of Good address days.
algae3113_pm10_rd_inv_addr_days The number of PM10 RD exposure days in the life stage that the study member spent at an invalid address. See definition of Invalid address days.
algae3114_pm10_rd_oob_days The number of PM10 RD exposure days in the life stage that the study member spent living at a location that is considered outside the bounds of the exposure area. See definition of Out of bounds days.
algae3115_pm10_rd_poor_addr_days The number of PM10 RD exposure days in the life stage that the study member spent living at a location whose geocode was derived from a poor quality residential address. The geocode was used to generate exposure values, but it is still considered to be invalid because it is of such poor quality. See definition of Poor address days.
algae3116_pm10_rd_missing_exp_days The number of PM10 RD exposure days in the life stage that the study member spent living at a valid geocode which has some exposure values but not for specific days. See definition of Missing exposure days.
algae3117_pm10_rd_good_addr_days The number of PM10 RD exposure days in the life stage that the study member spent living at a geocode that is considered a good match: it has a valid geocode and it has a non-blank exposure value for a given day. See definition of Good address days.
algae3118_pm10_gr_inv_addr_days The number of PM10 GR exposure days in the life stage that the study member spent at an invalid address. See definition of Invalid address days.
algae3119_pm10_gr_oob_days The number of PM10 GR exposure days in the life stage that the study member spent living at a location that is considered outside the bounds of the exposure area. See definition of Out of bounds days.
algae3120_pm10_gr_poor_addr_days The number of PM10 GR exposure days in the life stage that the study member spent living at a location whose geocode was derived from a poor quality residential address. The geocode was used to generate exposure values, but it is still considered to be invalid because it is of such poor quality. See definition of Poor address days.
algae3121_pm10_gr_missing_exp_days The number of PM10 GR exposure days in the life stage that the study member spent living at a valid geocode which has some exposure values but not for specific days. See definition of Missing exposure days.
algae3122_pm10_gr_good_addr_days The number of PM10 GR exposure days in the life stage that the study member spent living at a geocode that is considered a good match: it has a valid geocode and it has a non-blank exposure value for a given day. See definition of Good address days.
algae3123_pm10_tot_inv_addr_days The number of PM10 TOT exposure days in the life stage that the study member spent at an invalid address. See definition of Invalid address days.
algae3124_pm10_tot_oob_days The number of PM10 TOT exposure days in the life stage that the study member spent living at a location that is considered outside the bounds of the exposure area. See definition of Out of bounds days.
algae3125_pm10_tot_poor_addr_days The number of PM10 TOT exposure days in the life stage that the study member spent living at a location whose geocode was derived from a poor quality residential address. The geocode was used to generate exposure values, but it is still considered to be invalid because it is of such poor quality. See definition of Poor address days.
algae3126_pm10_tot_missing_exp_days The number of PM10 TOT exposure days in the life stage that the study member spent living at a valid geocode which has some exposure values but not for specific days. See definition of Missing exposure days.
algae3127_pm10_tot_good_addr_days The number of PM10 TOT exposure days in the life stage that the study member spent living at a geocode that is considered a good match: it has a valid geocode and it has a non-blank exposure value for a given day. See definition of Good address days.
algae3128_name_sum Cumulative exposure of NAME for the given life_stage.
algae3129_name_err_sum Cumulative exposure measurement error for NAME measured for the given life_stage
algae3130_name_avg Average exposure for NAME measured for the given life_stage
algae3131_name_err_avg Average exposure measurement error for NAME measured for the given life_stage
algae3132_name_med Median exposure for NAME measured for the given life_stage
algae3133_name_err_med Median exposure measurement error for NAME measured for the given life_stage
algae3134_nox_rd_sum Cumulative exposure of NOX (road sources) for a given life_stage.
algae3135_nox_rd_err_sum Cumulative exposure measurement error for NOX (road sources), measured for the given life_stage
algae3136_nox_rd_avg Average exposure of NOX (road sources) for a given life_stage.
algae3137_nox_rd_err_avg Cumulative exposure measurement error for NOX (road sources), measured for the given life_stage
algae3138_nox_rd_med Median exposure for NOX (road sources), measured for the given life_stage
algae3139_nox_rd_err_med Median exposure measurement error for NOX (road sources), measured for the given life_stage
algae3140_pm10_gr_sum Cumulative exposure for PM10 (non-road sources), measured for the given life_stage
algae3141_pm10_gr_err_sum Cumulative exposure measurement error for PM10 (non-road sources), measured for the given life_stage
algae3142_pm10_gr_avg Average exposure for PM10 (non-road sources), measured for the given life_stage
algae3143_pm10_gr_err_avg Average exposure measurement error for PM10 (non-road sources), measured for the given life_stage
algae3144_pm10_gr_med Median exposure for PM10 (non-road sources), measured for the given life_stage
algae3145_pm10_gr_err_med Median exposure measurement error for PM10 (non-road sources), measured for the given life_stage
algae3146_pm10_rd_sum Cumulative exposure for PM10 (road sources), measured for the given life_stage
algae3147_pm10_rd_err_sum Cumulative exposure measurement error for PM10 (road sources), measured for the given life_stage
algae3148_pm10_rd_avg Average exposure for PM10 (road sources), measured for the given life_stage
algae3149_pm10_rd_err_avg Average exposure measurement error for PM10 (road sources), measured for the given life_stage
algae3150_pm10_rd_med Median exposure for PM10 (road sources), measured for the given life_stage
algae3151_pm10_rd_err_med Median exposure measurement error for PM10 (road sources), measured for the given life_stage
algae3152_pm10_tot_sum Cumulative exposure for PM10 (all sources), measured for the given life_stage
algae3153_pm10_tot_err_sum Cumulative exposure measurement error for PM10 (all sources), measured for the given life_stage
algae3154_pm10_tot_avg Average exposure for PM10 (all sources), measured for the given life_stage
algae3155_pm10_tot_err_avg Average exposure measurement error for PM10 (all sources), measured for the given life_stage
algae3156_pm10_tot_med Median exposure for PM10 (all sources), measured for the given life_stage
algae3157_pm10_tot_err_med Median exposure measurement error for PM10 (all sources), measured for the given life_stage