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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for January 7th, 2021

Why a study with only 7 respondents can be good – from Dutch paper “De Volkskrant”

Posted by jpluimers on 2021/01/07

[] Waarom een onderzoek met maar 7 respondenten toch goed kan zijn | De Volkskrant: Denkfouten in het hedendaags ontwerp gefileerd door innovatie-expert (en cabaretier) Jasper van Kuijk. Deze week: gebruikstest.

Google translated in English.


Quantitative studies often require large numbers of respondents, but quantitative studies can be done with a very small group.

While quantitative studies often will get you just one result (I rate this application a 7 out of 10, or with this A/B change, click through increases by 5%), qualitative studies will get you much more specific comments like “the main menu is cluttered”, or “the design is slick” (translated from the Image in the article).

Extensive research was done for a 2003 published paper [] Beyond the five-user assumption: Benefits of increased sample sizes in usability testing which you can read as PDF [WayBack].


[WayBack] Jasper van Kuijk on Twitter: “Mijn ‘Hoe moeilijk kan het zijn?’ van vandaag. Waarom voor gebruiksgemak een gebruikstest met 7 participanten nuttiger is dan een enquête met 1500 respondenten. #HMKHZ via de @volkskrant”


[WayBack] Ionica Smeets on Twitter: “Hear, hear! Aldus een wiskundige die heel wat jaren nodig had om waarde van kwalitatief onderzoek in te zien…”




Read the rest of this entry »

Posted in Development, Software Development, Testing, Usability, User Experience (ux) | Leave a Comment »

Fiber cables: speed and connectors

Posted by jpluimers on 2021/01/07

Similar to the CAT# designation for speed categories, fiber cables have an OM# designation. [WayBack] OM1 fiber, OM2 fiber, OM3 fiber and OM4 fiber overview explain this well, and has this quote and image tables:

There are four kinds of multimode fibers: OM1 fiber, OM2 fiber, OM3 fiber and OM4 fiber. The letters “OM” stand for optical multi-mode.

Both OM1 and OM2 work with LED based equipment that can send hundreds of modes of light down the cable, while OM3 and OM4 are optimized for laser (eg. VCSEL) based equipment.

I have combined the tables in html as:

Maximum distance for 100 Mbit/s 2000m 2000m 2000m 2000m 100BASE -FX
Maximum distance for 1 Gbit/s 275m 550m 550m 1000m 1000BASE-SX
Maximum distance for 10 Gbit/s 33m 82m 300m 550m 10GBASE-SR
Maximum distance for 40 Gbit/s not specified not specified 100m 150m 40GBASE-SR4
Maximum distance for 100 Gbit/s not specified not specified 100m 150m 100GBASE-SR10 / 100GBASE-SR4
Diameter 62.5/125µm 50/125µm 50/125µm 50/125µm
Jacket coulors (often also cable colours) Orange Orange Aqua Aqua
Optical source LED LED VCSEL VCSEL
Bandwidth 200MHz*km 500MHz*km 2000MHz*km 4700MHz*km


Unlike CAT cabling, fiber cables can have various connectors, of which SC and LC are the most common as explained in [WayBack] SC vs LC—What’s the difference? which has this quote and image table:

  • Size: LC is half the size of SC. Actually, one SC-adapter is exactly the same size as a duplex LC-adapter. Therefore LC is more and more common in central offices where packing density (number of connections per area) is an important cost factor
  • Handling: SC is a true “push-pull-connector” and LC is a “latched connector”, although there are very innovative, real “push-pull-LCs” available which have the same handling capabilities like SC.
  • The History of Connector: The LC is the “younger” connector of the two, SC is wider spread around the world but LC is catching up. Both connectors have the same insertion loss and return loss capabilities. Generally, it depends where in the network you want to use the connector, no matter SC or LC, even the other different kinds of connector.

In html:

Name Mating
insertion loss
Cost Ease
SC 1000 Ø 2.5mm
0.25-0.5 61754-4 $$ ••••• Mainstream, reliable, fast deployment, field fit
LC 500 Ø 1.25mm
0.25-0.5 61754-20 $$ ••••◦ High density, cost effective, field fit



Posted in Ethernet, Network-and-equipment, Power User | Leave a Comment »

Named Pipes unit for Delphi | Mick’s Mix

Posted by jpluimers on 2021/01/07

[WayBack] Named Pipes unit for Delphi | Mick’s Mix  by Russell Libby, for which (Apr 7, 2013) Francoise Piette has updated this source code for Delphi XE3 and put it on his website at [WayBackOverByte – Blog Source Code as [WayBack]


Posted in Delphi, Development, Software Development | Leave a Comment »

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