Famous statistical quotations What is your favorite statistical quote?  
This is community wiki, so please one quote per answer.  
 A: 
Statistical thinking will one day be
  as necessary a qualification for
  efficient citizenship as the ability
  to read and write.

--H.G. Wells
A: 
The combination of some data and an
  aching desire for an answer does not
  ensure that a reasonable answer can be
  extracted from a given body of data

Tukey
A: 
These days the statistician is often
  asked such questions as "Are you a
  Bayesian?" "Are you a frequentist?"
  "Are you a data analyst?" "Are you a
  designer of experiments?". I will
  argue that the appropriate answer to
  ALL of these questions can be (and
  preferably should be) "yes", and that
  we can see why this is so if we
  consider the scientific context for
  what statisticians do.

--G.E.P. Box
A: 9 out of ten dentists think the 10th dentist is an idiot. 


*

*No idea who said it.

A: 
To understand God's Thoughts
  we must study statistics
  for these are the measure
  of His purpose.

--Florence Nightingale
A: 
The business of the statistician is to
  catalyze the scientific learning
  process.

George Box
A: 
[Statistics are] the only tools by which an opening can be cut through the formidable thicket of difficulties that bars the path of those who pursue the science of man.

-- Sir Francis Galton 
A: 
The probability is like the stick used by the blind man to feel his way. If he could see, he would not need the cane, just as if we knew which horse runs faster, then we would not need probability theory.

Stanislaw Lem
A: 
The roll of the dice will never abolish chance

Written in 1897 by Stéphane Mallarmé (1842-1898) , a famous French poet - In French : 

Un coup de dés jamais n'abolira le hasard

A: Context: An F-test is often a poor way to justify pooling, because F-test is not robust against non-normality.
"To make a preliminary test on variances is rather like putting to sea in a rowing boat to find out whether conditions are sufficiently calm for an ocean liner to leave port."  (G.E.P. Box, "Non-normality and tests on variances",
Source: Biometrika, 40 (1953), pp 318-335, quote on page 333; via from Moore & McCabe.
(props to Tim Hesterberg: https://stat.ethz.ch/pipermail/r-help/2008-February/154856.html)
A: People think that if you collect enormous amounts of data you are bound to get the right answer.  You are not bound to get the right answer unless you are enormously smart.  Bradley Efron
A: 

Uncertainty is a personal matter; it is not the uncertainty but
  your uncertainty. (Dennis Lindley)

Reference: Dennis Victor Lindley (2006), Understanding Uncertainty, Wiley-Interscience, p. 1.
A: 
There are no routine statistical
  questions, only questionable
  statistical routines.

D.R. Cox
A: 
Statistics - A subject which most statisticians find difficult but which many physicians are experts on. "Stephen S. Senn"

A: 
He uses statistics like a drunken man uses a lamp post, more for support than illumination.

-- Andrew Lang
A: 
Strange events permit themselves the
  luxury of occurring.

-- Charlie Chan
A: A nice one I came about:

I think it's much more interesting to live not knowing than to have answers which might be wrong.

By Richard Feynman (link)
A: 
"He who loves practice without theory
  is like the sailor who boards ship
  without a rudder and compass and never
  knows where he may be cast."
  - Leonardo da Vinci, 1452-1519 

Found here.
A: A quote from Karl Pearson: 

The unity of all science consists alone in its method, not in its material 

I think of statistics as, essentially, the methodology of science, so that's how I interpret this quote. 
A: "As far as the laws of mathematics refer to reality, they are not certain, as far as they are certain, they do not refer to reality."
albert einstein
A: 
The best thing about being a statistician is that you get to play in everyone's backyard.

-- John Tukey 
(This is MY favourite Tukey quote)
A: 
You may be too vague to be wrong and
  that's really bad cause that's just
  obscuring the issue.

Bruce Sterling 
A: "I cannot conceal the fact here that in the [application of probability theory], I foresee many things happening which can cause one to be badly mistaken if he does not proceed cautiously.",
Bernoulli (1713) (via ET Jaynes)
"A statistician is someone who knows what to assume to be Gaussian"
Dikran Marsupial (2009) (not famous yet ;o).
A: 
Everybody knows that probability and statistics are the same thing, and statistics is nothing but correlation. Now the correlation is just the cosine of an angle, thus all is trivial. 

-- Emil Artin, according to Kai Lai Chung in
Elementary probability theory (right, Artin might not been known primarily as a statistician)
A: 
The researcher armed with a confidence
  interval, but deprived of the false
  respectability of statistical
  significance, must work harder to
  convince himself and others of the
  importance of his findings. This can
  only be good.

Michael Oakes, Statistical inference: A commentary for the social and behavioural sciences  (NY: Wiley, 1986)
A: "The statistician cannot evade the responsibility for understanding the processes he applies or recommends."  -- Sir Ronald A. Fisher in The Design of Experiments (1935)
A: 
Absence of evidence is not evidence of absence.

–Martin Rees (Wikipedia)
A: 
"It's easy to lie with statistics; it is easier to lie without them."

-- Frederick Mosteller
A: 
Statistics are the triumph of the
  quantitative method, and the
  quantitative method is the victory of
  sterility and death.

~ Hillaire Belloc in The Silence of the Sea
A: 
We statisticians, as a police of
  science (a label some dislike but I am
  proud of...), have
  the fundamental duty of helping others
  to engage in statistical thinking as a
  necessary step of scientific inquiry
  and evidence-based policy formulation.
  In order to truly fulfill this task,
  we must constantly firm up and deepen
  our own foundation, and resist the
  temptation of competing for “methods
  and results” without pondering deeply
  whether we are helping others or
  actually harming them by effectively
  encouraging more false discoveries or
  misguided policies. Otherwise, we
  indeed can lose our identity, no
  matter how much we are desired or
  feared now.

Xiao-Li Meng
A: 
“Statistics is much like a streetlight. Not very enlightening, but nice for supporting you”

Storm P
A: We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.
Pierre-Simon de Laplace.  Also known as Laplace's demon
A: 
Statistics' real contribution to society is primarily moral, not technical. 

Steve Vardeman and Max Morris
A: "One death is a tragedy, 100,000 deaths are statistics."
Albert Szent-Gyorgyi 
A: 
"If you put a buttock on a hot plate and another one on an ice cube, the average is good, but in reality your bottom is in trouble."

Grigore Moisil
A: Not really about statistics, but works perfectly:
"Science is built up of facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house."  (Henri Poincaré)
A: Not yet famous, but could become so. 

"If a problem can not be tackled nonparametrically, it is dangerous to
  tackle it parametrically. But on the other hand, if it can be tackled
  nonparametrically, it would be better to tackle it parametrically."
  -- Sir David Cox 

Statistics - past, present and future, Royal Statistical Society 180th
Anniversary Lecture near 16:27.
A: 
Say you were standing with one foot in the oven and one foot in an ice bucket.  According to the percentage people, you should be perfectly comfortable.  

-Bobby Bragan, 1963
A: 
Tout le monde y croit cependant, me disait un jour M. Lippmann, car les expérimentateurs s'imaginent que c'est un théorème de mathématiques, et les mathématiciens que c'est un fait expérimental.

Henri Poincaré, Calcul des probabilités (2nd ed., 1912), p. 171.
In English:

Everybody believes in the exponential law of errors [i.e., the Normal distribution]: the experimenters, because they think it can be proved by mathematics; and the mathematicians, because they believe it has been established by observation.

Whittaker, E. T. and Robinson, G. "Normal Frequency Distribution." Ch. 8 in The Calculus of Observations: A Treatise on Numerical Mathematics, 4th ed. New York: Dover, pp. 164-208, 1967. p. 179.
Quoted at Mathworld.com.
A: 
My greatest concern was what to call
  it. I thought of calling it
  'information,' but the word was overly
  used, so I decided to call it
  'uncertainty.' When I discussed it
  with John von Neumann, he had a better
  idea. Von Neumann told me, 'You should
  call it entropy, for two reasons. In
  the first place your uncertainty
  function has been used in statistical
  mechanics under that name, so it
  already has a name. In the second
  place, and more important, no one
  really knows what entropy really is,
  so in a debate you will always have
  the advantage.'

Claude Elwood Shannon
A: I don't know about famous, but the following is one of my favourites:

Conducting data analysis is like
  drinking a fine wine. It is important
  to swirl and sniff the wine, to unpack
  the complex bouquet and to appreciate
  the experience. Gulping the wine
  doesn’t work.

-Daniel B. Wright (2003), see PDF of Article.
Reference:
Wright, D. B. (2003). Making friends with your data: Improving how statistics are conducted and reported1. British Journal of Educational Psychology, 73(1), 123-136.
A: 
... surely, God loves the .06 nearly as much as the .05. Can there be any
doubt that God views the strength of evidence for or against the null as a
fairly continuous function of the magnitude of p? (p.1277)

Rosnow, R. L., & Rosenthal, R. (1989). Statistical procedures and the justification of knowledge in psychological science. American Psychologist, 44(10), 1276-1284. pdf.
A: 
The Median Isn't the Message

--Stephen Jay Gould
A: 
The mathematician, carried along on his flood of symbols, dealing apparently with purely formal thruths, may still reach results of endless importance for our description of physical universe

-- Karl Pearson
A: No statistican, but useful for the profession:

The perfect is the enemy of the good 
  - Voltaire

A: CauseWeb has a collection of statistics quotations.  Many have already been repeated here, but it has plenty that haven't yet been quoted, such as

"The only statistics you can trust are those you falsified yourself."

(Falsely attributed to Sir Winston Churchill.)  For the rest, follow the CauseWeb links to Resources->Fun->Quote.
A: 
Good statistics involves principled argument that conveys an interesting and credible point.

-- Robert P. Abelson, (1995) "Statistics as Principled Argument"

We left in our mathematical model a gap for the exercise of a more intuitive process of personal judgement

-- Egon Pearson, quoted in Abelson (1995).
A: Check out "Statistician's Blues" by Todd Snider who is an alternative-country singer-songwriter.  Warning, if you are sensitive to "bad" words, don't listen to the song.  If you have a good or perhaps twisted sense of humor you will enjoy.
A: "Winwood Reade is good upon the subject. He remarks that, while the individual man is an insoluble puzzle, in the aggregate he becomes a mathematical certainty. You can, for example, never foretell what any one man will do, but you can say with precision what an average number will be up to. Individuals vary, but percentages remain constant. So says the statistician".
(Sherlock Holmes speaking to Dr. Watson in Arthur Conan Doyle's "The Sign of the Four")
A: A table without stars is like champagne without bubbles! - David Giles
A: 
Data analysis is simply a dialogue with the data

--Stephen F. Gull, 1994
A: 
Many folks know only enough statistics to be dangerous.
  From Statistics for Dummies II - Deborah Rumsey

A: 
All we know about the world teaches us that the effects of A and B are always different---in some decimal place---for any A and B. Thus asking "are the effects different?" is foolish.

Tukey (again but this one is my favorite)
A: 
On two occasions I have been asked [by
  members of Parliament], ‘Pray, Mr.
  Babbage, if you put into the machine
  wrong figures, will the right answers
  come out?’ I am not able rightly to
  apprehend the kind of confusion of
  ideas that could provoke such a
  question.

Charles Babbage
A: 
The subjectivist (i.e. Bayesian)
  states his judgements, whereas the
  objectivist sweeps them under the
  carpet by calling assumptions
  knowledge, and he basks in the
  glorious objectivity of science.

I.J. Good
A: 
Do not trust any statistics you did not fake yourself.

-- Winston Churchill
A: 
Do not make things easy for yourself
  by speaking or thinking of data as if
  they were different from what they
  are; and do not go off from facing
  data as they are, to amuse your
  imagination by wishing they were
  different from what they are. Such
  wishing is pure waste of nerve force,
  weakens your intellectual power, and
  gets you into habits of mental
  confusion.

--Mary Everest Boole
A: It's not really about statistics, but I think it applies to statistics:

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. 

Arthur Conan Doyle
A: 
[T]he p-value is the probability of obtaining data at least as
  extreme as the ones observed, if the null hypothesis is true. This is
  a world apart from saying that it is the probability of the null
  hypothesis being true, given that you observed that extreme data!
  Beware! If your ability on the long jump puts you in the 99.99%
  percentile, that does not mean that you are a kangaroo, and neither
  can one infer that the probability that you belong to the human race
  is 0.01%. - Tomasso Dorigo

A: This is unlikely to be a popular quote, but anyway,

If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford
A: 
"Million to one chances crop up nine times out of ten."

-Terry Pratchett
A: 
Those who ignore Statistics are condemned to reinvent it.

-- Brad Efron
A: 
Figures don't lie, but liars do figure

--Mark Twain
A: 
The plural of anecdote is not data.

-- Roger Brinner
(in the context of Anecdotal_evidence)
A: 
…the statistician knows…that in nature
  there never was a normal distribution,
  there never was a straight line, yet
  with normal and linear assumptions,
  known to be false, he can often derive
  results which match, to a useful
  approximation, those found in the real
  world.

George Box (JASA, 1976, Vol. 71, 791-799)
A: 
"The first time I was in a statistics course, I was there to teach it"

John Tukey (link)
A: 
The death of one man is a tragedy. 
  The death of millions is a statistic.

-- Kurt Tucholsky, in: Französischer Witz, 1925
A: 
"To find out what happens when you change something, it is necessary
  to change it.”

Box, Hunter, and Hunter, Statistics for Experimenters (1978).
A: "It is easy to lie with statistics. It is hard to tell the truth without statistics." - Andrejs Dunkels
A: 
An argument over the meaning of words
  is a matter of law, an argument
  grounded in empirical data and
  quantitative estimates is an argument
  about science.

~ Razib Khan (though he is not a statistician or famous)
A: A variation on the Fisher quotation given here is

Hiring a statistician after the data have been collected is like hiring a physician when your patient is in the morgue.  He may be able to tell you what went wrong, but he is unlikely to be able to fix it.

But I heard this attributed to Box, not Fisher.
A: Perhaps not overly famous among statisticians but reduced-form econometricians will know it well:

If you can't see the causal relation of interest in the reduced form, it's probably not there.

Angrist and Krueger (2001)
A: 
Statistics without science is incomplete, science without statistics
  is imperfect.

K.V. Mardia
A: 
An intense preoccupation with the latest minutiae and indifference to the social and intellectual forces of tradition and revolutionary change, combine to produce the Mandarinism that some would now say already characterizes academic statistical theory and is most likely to describe its immediate future.
The statisticians of the past came into the subject from other fields - astronomy, pure mathematics, genetics, agronomy, economics etc. — and created their statistical methodology with a background of training for a specific scientific discipline and a feeling for its current needs. So for the future I recommend we work on interesting problems and avoid dogmatism.

-- Herbert Robbins in "Wither Mathematical Statistics?" as quoted by Peter J. Huber in "Speculations on the Path of Statistics".
Robbins, Herbert. "Wither Mathematical Statistics?" Advances in Applied Probability 7 (1975): 116-21. doi:10.2307/1426316.
Brillinger, D. R., L. T. Fernholz, and S. Morgenthaler, eds. The Practice of Data Analysis: Essays in Honor of John W. Tukey. Princeton University Press, 1997. http://www.jstor.org/stable/j.ctt7zthdd.
A: In his Fisher lecture, Box defines mathematistry as 

the development of theory for theory's sake, which, since it seldom touches down with practice, has a tendency to redefine the problem rather than solve it. Typically, there has once been a statistical problem with scientific relevance but this has long since been lost sight of.

He also defines cookbookery as 

The tendency to force all problems into the molds of one or two routine techniques, insufficient thought being given to the real objectives of the investigation or to the relevance of the assumptions implied by the imposed methods.

References
Box, G. E. P. 1976. Science and Statistics. Journal of the American Statistical Association, 71: 791–799.
Roderick J. Little (2013) In Praise of Simplicity not Mathematistry! Ten Simple Powerful Ideas for the Statistical Scientist, Journal of the American Statistical Association
A: 
All models are wrong, but some are useful. (George E. P. Box)

Reference: Box & Draper (1987), Empirical model-building and response surfaces, Wiley, p. 424.
Also: G.E.P. Box (1979), "Robustness in the Strategy of Scientific Model Building" in Robustness in Statistics (Launer & Wilkinson eds.), p. 202.
A: 
I keep saying that the sexy job in the next 10 years will be statisticians. And I'm not kidding.

Hal Varian
A: 
We are drowning in information and starving for knowledge.

Rutherford D. Roger
A: 
The statistician cannot evade the responsibility for understanding the
  process he applies or recommends.

-– Sir Ronald A. Fisher
A: 
The greatest value of a picture is when it forces us to notice what we
  never expected to see.

-- John Tukey
A: 
"An approximate answer to the right problem is worth a good deal more than an exact answer to an approximate problem." -- John Tukey

A: 
There are three kinds of lies: lies,
  damned lies, and statistics.

-- probably: Charles Wentworth Dilke (1843–1911).
A: 
60% of the time, it works every time.

-Brian Fantana
A: 
Correlation doesn’t imply causation, but it does waggle its eyebrows suggestively and gesture furtively while mouthing ‘look over there’.

xkcd
A: "The Central Limit Theorem is about the journey and the Strong Law of Large Numbers is about the destination."  stats.SE user cardinal in a comment on this question
A: 
My thesis is simply this: probability does not exist.
  - Bruno de Finetti

A: 
The primary product of a research
  inquiry is one or more measures of
  effect size, not p values.

Cohen, J. (1990). Things I have learned (so far). American Psychologist, 45, 1304-1312.
A: 
A witty statesman said, you might
  prove anything by figures.

~ Thomas Carlyle, Chartism (1839) ch. 2
A: 
...Statistics used as a catalyst to engineering creation will, I believe, always result in the fastest and most economical progress.

--George Box 1992
A: This is a two part quote I've heard a few times:

Machine learning is statistics minus any checking of models and assumptions. 

Brian D. Ripley

In that case, maybe we should get rid of checking of models and assumptions more often. Then maybe we'd be able to solve some of the problems that the machine learning people can solve but we can't!

Andrew Gelman
Link (Ripley is quoted as making the statement at the useR forum, Gelman responds to the quote on his blog).
There's some irony in the sides taken by these two statisticians in this conversation. That is, some of Brian Ripley's early work was on Neural Networks, which is an extremely popular topic in Machine Learning, where as Andrew Gelman is exclusively known for Bayesian statistics in which he advocates taking one's statistical models very seriously. 
A: 
A statistical procedure is not an automatic, mechanical truth-generating machine 

Meehl (1992)
A: 
The problem of modern day governments is that they try to get more than half the people above the median levels of income, health, happiness, education etc.

A: 
The first principle is that you must not fool yourself—and you are the easiest person to fool.

Richard Feynman
http://calteches.library.caltech.edu/3043/1/CargoCult.pdf
A: 
While the individual man is an insoluble puzzle, in the aggregate he becomes a mathematical certainty. You can, for example, never foretell what any one man will be up to, but you can say with precision what an average number will be up to. Individuals vary, but percentages remain constant. So says the statistician.

Arthur Conan Doyle
A: "Extraordinary claims demand extraordinary evidence." 
Often attributed to Carl Sagan, but he was paraphrasing sceptic Marcello Truzzi. Doubtless the concept is even more ancient. 
David Hume said, "A wise man, therefore, proportions his belief to the evidence". 
One could argue this is not a quote about statistics. However, applied statistics is ultimately in the business of evaluating the quality of evidence for or against some proposition.
A: 
It ain’t what you don’t know that gets
  you into trouble. It’s what you know
  for sure that just ain’t so.

Mark Twain (okay, so he's not a statistician)
A: This one is brand new, and Allen Wilcox is an epidemiologist, not a statistician, but whatever, I'm running with it.

Data do not speak for themselves - they need context, and they need skeptical evaluation

A: 
If I can't picture it, I can't understand it.  

-Albert Einstein
I acknowledge that Einstein wasn't a statistician.  However, Michael Friendly uses this quote in arguing for a greater role for visualizations in data analysis.  I share that goal, and I think the quote works nicely.  
A: Without data you're just another person with an opinion. -- W. Edwards Deming

A: 
An ecologist is a statistician who likes to be outside. 

-- apparently a good friend of Murray Cooper.
A: May I add this one, because I like Jan's contributions to psychometrics and statistics...

Causal interpretation of the results
  of regression analysis of
  observational data is a risky
  business. The responsibility rests
  entirely on the shoulders of the
  researcher, because the shoulders of
  the statistical technique cannot carry
  such strong inferences.
Jan de Leeuw, homepage

A: 
The Earth is round.  p < .05

Jacob Cohen
A: 
When I see articles with lots of
  significance tests, I say that the
  statisticians are p-ing on the
  research.

Herman Friedmann (by recollection, he said this in class)
A: Found in Warning Signs in Experimental Design and Interpretation  by Peter Norvig

Most of the time, when you get an amazing, counterintuitive result, it means you have screwed up the experiment

(Michael Wigler)
in the sense of 

Extraordinary claims require extraordinary evidence

(Carl Sagan)
which is based on a similar quote by Pierre Laplace
A: I just can't help myself, this is a provocative quote from E. T. Jaynes:

Many of us have already explored the road you are following, and we
  know what you will find at the end of it.  It doesn't matter how many
  new words you drag into the discussion to avoid having to utter the
  word 'probability' in a sense different from frequency: likelihood,
  confidence, significance, propensity, support, credibility,
  acceptability, indifference, consonance, tenability; and so on, until
  the resources of the good Dr Roget are exhausted.  All of these are
  attempts to represent degrees of plausibility by real numbers, and
  they are covered automatically by Cox's theorems.  It doesn't matter
  which approach you happen to like philosophically; by the time you
  have made your methods fully consistent, you will be forced, kicking
  and screaming, back to the ones given by Laplace.  Until you have
  achieved mathematical equivalence with Laplace's methods, it will be
  possible, by looking in specific problems with Galileo's
  magnification, to exhibit the defects in your methods.

A: This is my favourite:

"To be sure of hitting the target, shoot first and call whatever you
  hit the target.”

by Ashleigh Brilliant
A: 
"To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of."

-- Ronald Fisher (1938)
The quotation can be read on page 17 of the article.
R. A. Fisher. Presidential Address by Professor R. A. Fisher, Sc.D., F.R.S. Sankhyā: The Indian Journal of Statistics (1933-1960), Vol. 4, No. 1 (1938), pp. 14-17. 
http://www.jstor.org/stable/40383882
A: 
It is the mark of a truly intelligent
  person to be moved by statistics.

George Bernard Shaw
A: 
It would be illogical to assume that
  all conditions remain stable

~ Spock, "The Enterprise Incident",stardata 5027.3
A: Torture numbers, and they'll confess to anything.  ~Gregg Easterbrook
A: 
Anyone who considers arithmetical
  methods of producing random digits is,
  of course, in a state of sin.

-- Von Neumann
A: 
Numerical quantities focus on expected values, graphical summaries on
  unexpected values.

--Tukey
A: "...a false premise built into a model which is never questioned cannot be removed by any amount of new data." 
E.T. Jaynes
A: 
87% of statistics are made up on the spot

-Unknown

Dilbert.com
A: preamble: There is even a class of user now days who sees the signiﬁcance stars  rather like the gold stars my grandson sometimes gets on his homework:

Three solid gold (significance) stars
  on the main effects will do very
  nicely, thank you, and if there are a
  few little stars here and there on the
  interactions, so much the better!

W.N. Venables 
Exegeses on Linear Models
A: "Taking a model too seriously is really just another way of not taking it seriously at all."
By Andrew Gelman
A: 
In God we trust. All others must bring
  data. 

(W. Edwards Deming)
A: 
Statisticians, like artists, have the bad habit of falling in love with their models.

-- George Box
A: 
Statistics are like bikinis.  What
  they reveal is suggestive, but what
  they conceal is vital.

-Aaron Levenstein
A: Everybody is a Bayesian. It's just that some know it, and some don't.
- Trivellore Raghunathan
A: 
Don't think -- use the computer.

Attributed ("tongue in cheek," just to make sure we understand the intent) to "G. Dyke."  Quoted in Phillip I. Good and James W. Hardin, Common Errors in Statistics: see the very first page of Part I.

A "G. Dyke" is cited in the bibliography as the author of How to avoid bad statistics.  Field Crops Res. 1997; 51: 165-197.  This apparently is George Dyke, who later in the book is quoted more at length:

The availability of 'user-friendly' statistical software has caused authors to become increasingly careless about the logic of interpreting their results, and to rely uncritically on computer output, often using the 'default option' when something a little different (usually, but not always, a little more complicated) is correct, or at least more appropriate.

[Cited on pp 71-72 in the first edition, 2003.]
A related quotation graces the beginning of Chapter 7:

Cut out the appropriate part of the computer output and paste it onto the draft of the paper.

A: 
"Statistics is exciting because you get to play with others' data
  while telling them their research is crap."

Stephen J. Senn (Source)
A: Data is the sword of the 21st century, those who wield it well, the Samurai.
A: "If you think that statistics has nothing to say about what you do or how you could do it better, then you are either wrong or in need of a more interesting job." - Stephen Senn (Dicing with Death: Chance, Risk and Health, Cambridge University Press, 2003)
A: 
"New methods always look better than old ones. Neural nets are better
  than logistic regression, support vector machines are better than
  neural nets, etc." - Brad Efron

A: 
In the long run, we're all dead. 

-- John Maynard Keynes. 
A reference to survival analysis?!
A: 
At their best, graphics are instruments for reasoning.
Edward Tufte,  www.edwardtufte.com

A: "After 17 years of interacting with physicians, I have come to realize that many of them are adherents of a religion they call Statistics... Like any good religion, it involves vague mysteries capable of contradictory and irrational interpretation. It has a priesthood and a class of mendicant friars. And it provides Salvation: Proper invocation of the religious dogmas of Statistics will result in publication in prestigious journals."
David S. Salsburg (author of The Lady Tasting Tea), quoted at "Pithypedia".
A: One sees, from this Essay, that the theory of probabilities is basically just common sense reduced to calculus; it makes one appreciate with exactness that which accurate minds feel with a sort of instinct, often without being able to account for it.
Another one from Laplace
A: 
With three constants, I can fit a dog. With four, I can make it bark.

Attributed to William Reifsnyder, in a personal communication to me. Unfortunately I can't find a reference on the 'web.
A: Statistics is the grammar of science - Karl Pearson
A: 
Prediction is very difficult, especially about the future.

-- Niels Bohr
A: 
If you torture the data enough, nature will always confess.  

--Ronald Coase (quoted from Coase, R. H. 1982. How should economists chose? American Enterprise Institute, Washington, D. C.).  I think most who hear this quote misunderstand its profound message against data dredging.
A: 
The true logic of this world is in the calculus of probabilities.

-- James Clerk Maxwell
A: 
All information looks like noise until you break the code.

Hiro in Neal Stephenson's Snow Crash (1992)
A: 
There is no free hunch.

-- Robert Abelson
A: 
Though this be madness, yet there is method in't.

William Shakespeare, Hamlet Act 2, scene 2, 193–206 
Not quite from a statistician, but I nonetheless like to quote this one in lectures. It nicely sums up what we as data analysts do.
A: "What the use of a p-value implies, therefore, is that a hypothesis that may be true may be rejected because it has not predicted observable results that have not occurred."
Harold Jeffreys (Theory of Probability)
A: The best time to plan an experiment is after you've done it. 
by R.A. Fisher
A: 
“There are two things you are better off not watching in 
  the making: sausages and econometric estimates.” - Edward Leamer

The quote comes from:
Leamer, Edward E, 1983. "Let's Take the Con Out of Econometrics," American Economic Review, American Economic Association, vol. 73(1), pages 31-43, March.
And he also says it, in spoken word, on this EconTalk podcast hosted by Russ Roberts.
A: "When physicists do mathematics, they don’t say they’re doing “number science”. They’re doing math. If you’re analyzing data, you’re doing statistics. You can call it data science or informatics or analytics or whatever, but it’s still statistics." - Karl Broman 
A: 
All generalizations are false,
  including this one.

Mark Twain
A: 
A big computer, a complex algorithm and a long time does not equal science.

-- Robert Gentleman
A: 
efficiency = statistical efficiency x usage.

-- John Tukey
A: 
A statistical analysis, properly conducted, is a delicate dissection of uncertainties, a surgery of suppositions.   

-- M.J. Moroney
A: A bit obscure this one, but a great quote about subjective probability:

... There is no way, however, in which the individual can avoid the
  burden of responsibility for his own evaluations. The key cannot be
  found that will unlock the enchanted garden wherein, among the
  fairy-rings and the shrubs of magic wands, beneath the trees laden
  with monads and noumena, blossom forth the flowers of probabilitas
  realis. With these fabulous blooms safely in our button-holes we would
  be spared the necessity of forming opinions, and the heavy loads we
  bear upon our necks would be rendered superflous once and for all.

Bruno de Finetti, Theory of Probability, Vol 2
A: 
A man who ‘rejects’ a hypothesis provisionally, as a matter of habitual practice, when the significance is at the 1% level or higher, will certainly be mistaken in not more than 1% of such decisions. For when the hypothesis is correct he will be mistaken in just 1% of these cases, and when it is incorrect he will never be mistaken in rejection. [...] However, the calculation is absurdly academic, for in fact no scientific worker has a fixed level of significance at which from year to year, and in all circumstances, he rejects hypotheses; he rather gives his mind to each particular case in the light of his evidence and his ideas.
-- Sir Ronald A. Fisher, from Statistical Methods and Scientific Inference (1956)

Another quote as a commentary: "This passage clearly is intended as a criticism of Neyman and Pearson, although again their names are not mentioned. However, these authors never recommended a fixed level of significance that would be used in all cases. [...] Thus Fisher rather incongruously appears to be attacking his own past position rather than that of Neyman and Pearson" (from Fisher, Neyman, and the Creation of Classical Statistics by Erich Lehmann, section 4.5).
A: 'Figures fool when fools figure'.
Henry Oliver Lancaster
A: 
"A frequentist is a person whose long-run ambition is to be wrong 5% of the time."

Unknown.
A: 
Bayesians address the question everyone is interested in by using assumptions no-one believes, while frequentists use impeccable logic to deal with an issue of no interest to anyone

Louis Lyons
A: 
The Government are very keen on amassing statistics—they collect them, add them, raise them to the nth power, take the cube root and prepare wonderful diagrams. But what you must never forget is that every one of those figures comes in the first instance from the chowkidar (village watchman), who just puts down what he damn pleases [link].

-- Josiah Stamp, recounting a story from Harold Cox, Some Economic Factors in Modern Life (1929), p. 258.
A: 
You complain that your report would be dry. The dryer the better. Statistics should be the dryest of all reading.

-- Florence Nightingale, fellow of the Royal Statistical Society, pioneer in data visualization and founder of modern nursing
A: 
Let’s be clear: the work of science
  has nothing whatever to do with
  consensus. Consensus is the business
  of politics. Science, on the contrary,
  requires only one investigator who
  happens to be right, which means that
  he or she has results that are
  verifiable by reference to the real
  world. In science consensus is
  irrelevant. What is relevant is
  reproducible results. The greatest
  scientists in history are great
  precisely because they broke with the
  consensus.
There is no such thing as consensus
  science. If it’s consensus, it isn’t
  science. If it’s science, it isn’t
  consensus. Period.

Michael Crichton
