The Series with Elastic Extents Problem (SWEEP)
"Gerrymandering" Urban Time Series
Sam Stehle / @sam_stehle
Building City Dashboards
National Centre for Geocomputation, Maynooth University, Maynooth Ireland
GISRUK 2019, Newcastle University
Hi I'm sam. I'm going to talk about the temporal equivalent to the Modifiable Areal Unit Problem - also known as the
Modifiable Temporal Unit Problem. Since you can't pronounce MTUP, I adopted the SWEEP acronym for the purpose of this talk.
The Modifiable Areal Unit Problem
Parallels in time: The SWEEP
Dublin Sound monitoring
http://dublincitynoise.sonitussystems.com/applications/api/dublinnoisedata.php?location=7&start=1554218025&end=1554822825
Dublin Agglomeration Environmental
Noise Action Plan (Nov. 2018)
Threshold (db) Daytime (07:00 - 19:00) nighttime (23:00 - 07:00)
Quiet Area
<55
<45
Desirable Low
<55
<50
Undesirable High
>70
>55
testing for SWEEP effects
(log) mean decibel level
frequency of observations which breach value limits
higher than 'undesirable high'
higher than 'desirable low'
lower than 'quiet area'
for each separate value limit, night and day
Blessington Street Basin
mean skewness of 5-minute observations = 0.251
Implications of scalar SWEEP effects
except in extreme cases, aggregating yields higher mean db values
meaning more frequent passing of high thresholds
and less frequent satisfaction of quiet area thresholds
1-hour aggregation as 12 segmentations
segmentation effects
mean time of day of :00 segment: 11:30
mean time of day of :55 segment: 12:25
segmentation and trend
Stations with quiet area SWEEP effect Stations with undesirable high SWEEP effect observations with increasing trend
Daytime
67%
20%
49.4%
Nighttime
80%
73%
79.7%
implications of segmentation effects
Increasing trend influences segmentation effect
SWEEP effects depend on how day/night times are defined (boundary effects)
Quiet area threshold is more volatile that undesirable high
anything more than a theoretical exercise?
while space is continuous, time is discretised, forming logical boundaries
considering intent: gerrymandering time series
Communication: portray low sound to the public
report disaggregated observations
Incentive/Disincentive schemes: reward low/punish high sound
no more cynical than political gerrymandering
Concluding recommendations
Standards for environmental reporting, especially when incentivised
Further reflection on the impact of stationarity, variability, boundary definitions
Streaming data for official statistics
Measure the impact of day of week - noncontiguous segmentations
Uncertain Geographic Context Problem (Kwan 2012)
Sam Stehle
Sam.Stehle@mu.ie
@sam_stehle
dublindashboard.ie
dashboards.maynoothuniversity.ie
The Series with Elastic Extents Problem (SWEEP)
"Gerrymandering" Urban Time Series
Sam Stehle / @sam_stehle
Building City Dashboards
National Centre for Geocomputation, Maynooth University, Maynooth Ireland
GISRUK 2019, Newcastle University
Hi I'm sam. I'm going to talk about the temporal equivalent to the Modifiable Areal Unit Problem - also known as the
Modifiable Temporal Unit Problem. Since you can't pronounce MTUP, I adopted the SWEEP acronym for the purpose of this talk.
