Why You Should Not Use Wikipedia As Your Primary Source

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It is no secret to anyone who has read my posts in this forum for a while that I do not like Wikipedia. I think that there’s a fundamental flaw with the whole concept and philosophy of it. While I think that it may be useful to many who need a quick lookup for something, it is unfortunate that even more are using it almost as their primary source of information. And this is scary considering that (i) the validity of the information being presented is never guaranteed and (ii) the pedagogical presentation of the material is often shoddy, making the subject even more confusing.

I often get asked to look at such-and-such Wikipedia entry, or someone is trying to convince me of something and using a Wikipedia entry as a “reference” to back up his/her argument. It is usually during such instances that I find inaccuracies, confusing statements, and something outright errors in such entries. I was doing my own search on something a few minutes ago, and I decided, out of curiosity, to see what Wikipedia has to say about “Work Function”. Now, keep in mind that this is a common terminology, especially for physics students, since the photoelectric effect is a “must-know” topic for these students. One would think that this should be a topic that a Wikipedia entry would get it right, considering how many people would look up such a thing, AND, the fact that errors and inaccuracy would, by now, be ironed out.


This is what I first saw on the Wikipedia page Oct. 8, and my last check today shows that it is still there.

work function wiki page

I posted the date in the screen capture as a date stamp on when this was first viewed.

The offending passage has been highlighted with a red box. Let’s look at it closely, shall we?

The description here is on what happened for an insulator (or a semiconductor, for that matter). The figure shown is the simplified band diagram for such a system (i.e. an intrinsic semiconductor, for example), and defines the various quantities such as the work function, band gap, electron affinity, etc. The problematic statement says this:

For an insulator, the Fermi level lies within the band gap, indicating an empty conduction band; in this case, the minimum energy to remove an electron is about the sum of half the band gap and the electron affinity.

The first part of that paragraph which says “…. For an insulator, the Fermi level lies within the band gap, indicating an empty conduction band …” is OK. However, the second part is very puzzling and an outright error : “… in this case, the minimum energy to remove an electron is about the sum of half the band gap and the electron affinity …”

Whoever wrote this is STILL thinking that the work function (Phi) is still the minimum energy needed to produce photoemission, as in the case of a metal. This is FALSE, and anyone who looks at the band diagram can tell. Half of the band gap plus the electron affinity is the work function Phi, but this is the energy between the vacuum level and the Fermi level. The Fermi level for insulator/semiconductor has NO STATES, and thus, no electrons to excite! After all, it resides in the band gap! So what is being excited here?

For an insulator/semiconductor, while the work function may still be defined as the energy between the Fermi level and the vacuum level, it no longer corresponds to the photoemission threshold! The photoemission threshold now is the full band gap energy PLUS the electron affinity. You need to excite, at the minimum, the electrons from the top of the valence band to the vacuum level. One can see this clearly by looking at the band diagram in the figure.

Now, you can tell me “But ZapperZ, why can’t you correct these errors, and provide a service to the community?” You will then have missed my point entirely. My problem isn’t with these errors. My problem is the WHOLE PHILOSOPHY of Wikipedia. I find that to be the fundamental flaw, that no one of any authority is being given the ability to write and edit stuff. The errors in the various entries are only the SYMPTOMS of the flawed philosophy. I could spend a lifetime correcting many of these errors (now why would I want to spend a lot of my own personal time to do that in the first place, no one has given me a good reason), and it would not change a thing about my perception of Wikipedia.

If you don’t know the topic you are looking up, and you are using Wikipedia as your PRIMARY SOURCE OF INFORMATION, I would be very scared if I were you.

108 replies
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  1. Dr. Courtney
    Dr. Courtney says:

    A few years back, my colleagues and I in the math dept at USAFA realized how commonly students accessed the wiki articles on basic math and Calculus topics. We realized that it would be much easier to improve the relevant articles and thus improve education for millions of students than change student behavior, which would only help our own students.

    A lot of the articles in math are pretty good since faculty at a number of institutions have been contributing to them. I suppose some purists are still offended by occasional errors. But a student making an effort to look stuff up on Wikipedia is a positive sign compared with the average effort expended by college students these days, and it seems easier to me to work harder to ensure that the effort yields productive outcomes than to try and redirect the efforts.

    I don’t see why a concerted effort from physicists couldn’t make the physics related pages worthy of student attention. No one will stem the tide of students looking at them unless they can convince Google to stop putting them in the top three results of most searches on academic type subjects. Pages that my wife and I have improved have been visited many millions of times since we improved them. We’ll never touch that many lives in the classroom, and we’ll never be able to make that many students look elsewhere.

  2. NickAtNight
    NickAtNight says:

    The simplest way to cure someone from using Wikipedia as a source is to edit a Wiki page in front of them. There are many noncontroversial pages that are open to an easy quick edit.

    Perhaps a quick story about the person being accused of being a witch, weighed on fixed scales to see if they weigh the same as a duck, and then… well, you most probably know the Monty Python scene from their movie.

    If you are real daring, you could change the particular material that they referenced into utter rubbish. Just be sure to fix what you break after you finish the lesson.

  3. Dr. Courtney
    Dr. Courtney says:

    It’s hard to blame students for preferring sources that may only be 90-95% accurate but are understandable over sources that may be 99+% accurate but not understandable.

    In my experience, students only turn to Wikipedia after having made some efforts understanding the material presented in their book and the lecture. I would be happy if most of my students ended the calculus semester with anything approaching the accuracy and mastery of the 50 most applicable Wikipedia articles.

    Until you can provide sources that are both perfectly accurate and perfectly understandable to all students, you shouldn’t criticize the use of alternate sources in the search for understandability. Would you criticize students for working together? I bet most Wikipedia articles are more accurate than most other students in the course. The caveats need to be understood, but the caveats do not mean the resource should be avoided.

  4. Torbjorn_L
    Torbjorn_L says:

    “I do not like Wikipedia”.

    That is an opinion, and totally irrelevant to if it is useful. It is as good as any other encyclopedia, so can be used for pithy introductions with care. It is better than any other encyclopedia, when used in courses and even papers for that purpose, something few other encyclopedias can be seen to do.

    And reading the article, it is immediately apparent why an opinion instead of usefulness has been the vehicle: unrealistic or misunderstood expectations on such a source. ” One would think that this should be a topic that a Wikipedia entry would get it right, considering how many people would look up such a thing, AND, the fact that errors and inaccuracy would, by now, be ironed out. … flawed philosophy.”

    What reader, educator or researcher would have such an expectation, or try to expose themselves or others to the problems that follow from uncritical reading? This is an example of why You Should Not Use Opinions Nor Philosophy As Your Primary Source.

    (And notably the “philosophy” of the author doesn’t work, since expert written encyclopedia articles are no better on average than Wikipedia articles. [Wikipedia. =D But really, they back it up with statistics, arguable or not.] )

    So as usual, use what works and expect YMMV.

  5. Geometry_dude
    Geometry_dude says:

    I like wikipedia. I know it’s not always correct and personally I’ve read entire articles that are bullocks, but I still like it, because it usually gives a nice intuitive introduction to a topic that is hard to get in a proper book.
    Personally, I have made it a custom to first read the wikipedia article about a topic, be very critical about it and then get to the actual literature with a glimpse of what it’s all about that I wouldn’t have otherwise.

    If you find an error in wikipedia, then just correct it or at least criticize it in the discussion. Also I think you are being delusional if you think that peer-reviewed journals and academic books are error free and don’t have nonsense-articles or statements. Think for yourself, you can obviously do it! No automaton can replace personal scepticism.

    It appears to me that you’re having trouble grasping the entire open-source idea. Do you like arxiv?

  6. verty
    verty says:

    Wikipedia follows the example of the famous French [url=http://en.wikipedia.org/wiki/Encyclop%C3%A9die]Encyclopédie[/url] of 1750-1770:

    [quote]The Encyclopédie was an innovative encyclopedia in several respects. Among other things, it was the first encyclopedia to include contributions from many named contributors, and it was the first general encyclopedia to lavish attention on the mechanical arts. Still, the Encyclopédie is famous above all for representing the thought of the Enlightenment. According to Denis Diderot in the article “Encyclopédie”, the Encyclopédie’s aim was “to change the way people think”. He wanted to incorporate all of the world’s knowledge into the Encyclopédie and hoped that the text could disseminate all this information to the public and future generations.[/quote]

    It sounds very familiar, doesn’t it? Is it a coincidence that so many advances were made only a few generations later? I mean steam power, metallurgy, etc. By ~1870, the world was essentially modern as far as scientific thinking goes. That’s within one lifetime of the encyclopedia’s publication.

    [quote]The encyclopedians successfully argued and marketed their belief in the potential of reason and unified knowledge to empower human will and thus helped to shape the social issues that the French Revolution would address. Although it is doubtful whether the many artisans, technicians, or laborers whose work and presence and interspersed throughout the Encyclopédie actually read it, the recognition of their work as equal to that of intellectuals, clerics, and rulers prepared the terrain for demands for increased representation. Thus the Encyclopédie served to recognize and galvanize a new power base, ultimately contributing to the destruction of old values and the creation of new ones.[/quote]

    This may be overstated but the fact remains, many people were empowered to make better decisions and to think in a new way, thanks to the disseminated knowledge. The world in 1750 was positively primordial, I think this encyclopedia must have had a huge influence.

    So what is the philosophy of Wikipedia? I believe it is to spread knowledge and effect the future in a positive way. Does it do that, will it do that? Time will tell, but there are countries that are not all that different to the world of 1750, and it could have a similar effect today in those countries, I’m thinking of countries like Indonesia, Myanmar, etc.

    That said, ZapperZ was careful to limit his admonishing to those who would use Wikipedia as a primary source. But as a secondary source, it is surely good and definitely worth having around, I think. If editing can make it better, edit away.

    Thank you.

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