Is dirty delicious?
Analysis: Gaille Teo | Visualisation: Lin Zhaowei & Gaille Teo
We all have that one friend who fervently believes that “the dirtier the kway chap, the tastier it is”.
Are they right? Is hawker food dirty, and does a dash of dirt add flavour to your dish?
The Data
To ensure that food is clean and safe for consumption, the National Environment Agency (NEA) issues grades to every licensed food outlet. Whether it’s hawker fare or haute cuisine, rest assured that the outlet you’re eating in has been inspected: Is food handled with clean hands? Is thawed meat safely stored in the chiller? Is food left in the open for too long? The NEA grading system works just like the good ol’ academic grades of our school days: you get an ‘A’, ‘B’, ‘C’, or ‘D’, and no one likes to fail.
Retail food establishments are graded based on their overall hygiene, cleanliness, and housekeeping standards:
All food outlets are advised to display the certificate indicating their grade.
On top of assigning grades, the NEA issues demerit points for food hygiene offences:
Offences which are assessed to be of high risk and impact on food safety are accorded more demerit points, whereas offences which are assessed to be of lower risk or are administrative in nature are accorded lower or no demerit point (from NEA website).
Offences are categorised as:
If a licensee accumulates 12 demerit points or more within 12 months, his license will either be suspended for 2 weeks or 4 weeks, or be revoked, depending on past suspension records.
The grades, demerit points, and suspension history of all NEA licensed eating establishments for the past 1 year is publicly available.
Where are the ‘dirtier’ food outlets?
NEA hasn’t awarded any ‘D’ grades in the past year, so the lowest grade given to any outlet is a ‘C’. The vast majority of food outlets get an ‘A’ or ‘B’, as seen in the gif below:
But what each of us really wants to know is: are there any ‘C’ outlets close to my house? In the map below, the deepest red shapes are the densest residential areas in Singapore… and you’ll be happy to know that the ‘C’ grade outlets do not cluster in those areas.
And maybe you’re worried that ‘C’ grade outlets can be found in cramped spaces where people are being squeezed out by city developments… Using Singapore’s road network as a proxy for urban growth, the map below also shows that ‘C’ grade outlets are not clustering in our country’s crowded corners.
Are hawkers dirty?
You’re probably dying to know if your favourite hawker haunt is clean or dirty, so here’s all the background information you need to know:
- There are 36,687 outlets in the NEA food grade dataset, and 5,642 are hawker stalls.
- Each hawker centre is made up of a mix of ‘A’, ‘B’, and ‘C’ food stalls.
- Singapore’s largest hawker centre — Smith Street’s Chinatown Complex Food Centre — has over 200 many hawker stalls but has very few ‘C’ stalls.
- Only one hawker centre — Blk 221A/B, Boon Lay Place — stands out in the chart below as having relatively more ‘C’ stalls when compared with other hawker centres:
As there are no ‘D’s in the NEA dataset, we discuss relative cleanliness by comparing the distribution of ‘A’ to ‘C’ food grades. It turns out that there are actually fewer ‘C’ graded hawkers compared to non-hawkers, both in terms of absolute numbers and proportion.
Further, hawkers get fewer demerit points than non-hawkers, regardless of grade:
Demerit Points vs Suspensions
One assumption is that outlets with lower grades get more demerit points: it seems intuitive that ‘C’ hawkers are dirtier than ‘B’ hawkers, and ‘B’ hawkers are dirtier than ‘A’ hawkers. In this train of thought, NEA grades should distinguish dirtier outlets by issuing ‘D’ and ‘C’ outlets with more demerit points than ‘B’ and ‘A’ outlets.
But this assumption is upended by the data. Although it seems intuitive that ‘C’ outlets should have more demerit points than ‘A’ and ‘B’ outlets, the track record reveals the exact opposite.
Just like the academic grading system, we have expectations about what each grade should mean: we anticipate ‘A’ food outlets to be cleanest, so ‘D’ grade outlets should get the most demerit points. But, looking at demerit points, food grades seem more like Tinder pictures instead — since it can only provide snapshots of the object of your desire, a grade alone cannot substantially distinguish between riskier and safer food choices.
A second assumption is that outlets with lower grades should get more suspensions. So we zoom into the number of suspensions for each grade:
As seen in the chart above, getting a lower grade like ‘C’ is definitely linked to getting suspended. (Note: This was verified with a Chi-square test of independence, p-value = 1.5392e-33.)
What does all this mean for you and me? As a consumer, instead of just paying attention to the simplistic letter grades of each outlet, I’ll also look out for suspensions at places that I visit frequently.
So is dirtier more delicious?
With the data at hand, we can compare the tastiness of ‘A’ versus ‘C’ grade outlets, as well as suspended versus non-suspended outlets.
Out of the 222 ‘C’ grade outlets, few (22) are hawkers, and even fewer have an online presence. Only 2 ‘C’ grade hawkers have a Yelp business profile with ratings and reviews given by customers. This results in a grand total of 25 reviews and a very average average of 3.5 Yelp stars — with too small a sample size, we move on to the second comparison of suspended versus non-suspended outlets.
Out of the 120 outlets that have been suspended in the past year, 23 have a Yelp profile. For a fair comparison, we sampled 23 Yelp profiles of non-suspended outlets to compare what customers were saying in reviews.
Most writers don’t seem to be concerned about the cleanliness of suspended outlets — they are usually raving about the food. In fact, most reviews are full of praise. The most commonly used words in the reviews for suspended and non-suspended outlets are:
But the ratings tell us that consumers probably view non-suspended food outlets more favourably overall:
While people do give suspended outlets a slightly above average rating of 3.14 Yelp stars, that still falls short of the 3.96 Yelp stars that non-suspended outlets receive.
Non-suspended outlets also seem to generate more buzz among consumers, as they accumulate more reviews than suspended outlets.
So, in this world of hyper-connected social networks like Facebook and Snapchat, don’t let a dash of dirt put you in hot water.
