Thursday, July 16, 2020

Review of Hoover : an extraordinary life in extraordinary times by Kenneth Whyte

This biography is a well written look at one of the most interesting and accomplished men of the twentieth century. It is long, but Hoover did so much I'm not sure how you make it shorter. Going in, I knew little beyond he did some humanitarian work during WWI and was the president during the start of the great depression. I knew from other readings that he wasn't to be blamed for the depression and that the start of FDR's first term was a continuation of Hoover's policies. I know believe that to understand America during the first half of the twentieth century you need to study three people:
  1. Theodore Roosevelt
  2. FDR
  3. Hoover
My favorite quote is from June of 1968 when Bobby Kennedy, while running for the Democratic nomination, was asked by David Frost in a live television interview which historical character he admired most:
I admire still a lot in Herbert Hoover’s career. I thought that his career and his earlier career and what he did working in the mines and his career in China, what he did for Europe after the First World War and what he did during the 1950s, the Hoover Commission of the United States, were just marvelous contributions to our country and to his fellow man. Of course, the difficulties that he had in the nineteen twenties as part of the cabinet and while he was president of the United States, but when you consider his overall career there were some marvelous things that he did.
Interesting stuff:
  • He died shortly after his 90th birthday, only two former presidents lived longer (Adams by 176 days and Carter still going at 95)
  • He was born into a Quaker family in Iowa, and was orphaned at 11. Around 2, when his family had given him up as dead an uncle, Dr Minthorn, who would later raise him, revived him.
  • "Hoover received the first room assignment under the red-tiled roof of Encina Hall, the men’s dormitory, allowing him to claim throughout his life that he was Stanford’s first student."
  • "When former United States president Benjamin Harrison attended a Stanford baseball game without a ticket, Hoover confronted him and quietly insisted he pay the admission price."
  • "The London firm of Bewick, Moreing and Company cabled its connections in San Francisco in October 1896 seeking recommendations for experienced American mining engineers for service in its Australian goldfields. The salary was reported to be $5,000 per annum, more than double Hoover’s pay. The minimum age requirement was thirty-five years. Janin, a generous soul, recommended this plum position to his prized employee, never mind that he was twenty-two years of age and a geologist rather than an engineer."
  • He met his wife, Lou, at Stanford. After being reassigned to Chine: "Hoover cabled Lou a brief message: “Going to China via San Francisco. Will you go with me?” She answered with a single word.
  • During the Boxer rebellion in 1900, "Hoover fought fires in the settlement and delivered food and medical supplies on his bicycle, hugging the brick walls along the street to avoid gunfire. Reporters on the scene observed that he seemed to be moving on the double quick, furiously jingling the change in his pockets and chewing nuts without shucking them. Lou, unwilling to join other women in the safety of the basement at city hall, ran bicycle errands of her own, a .38 Mauser strapped to her hip."
  • His first two children, Herbert Charles Hoover Jr and Allan Henry, were born in London where he was based until WW1. "From 1907 to 1910, Hoover had made only a single trip to his native land"
  • He published his first book, Principles of Mining, in 1909. When he died he was working on his 16th, Freedom Betrayed, that was published in 2012.
  • Hoover chaired the Committee of American Residents in London for the Assistance of American Travelers. "More than forty-two thousand individuals had registered with his organization and many more besides had benefited from its work. In excess of $400,000 had been distributed"
  • Hoover chaired the Committee for the Relief of Belgium (CRB) "In thirty months, the CRB had spent $200 million and shipped 2.5 million tons of food. By the peace, the total relief distributed would amount to $865 million (the U.S. government eventually kicked in as much as $20 million a month), with only $4 million of the total going to administrative overhead, a detail in which Hoover took great pride. It was, as Lord Curzon remarked, “an absolute miracle of scientific organization. Every pound of food and supplies is accounted for.”
  • For his efforts Lord Kitchener asked him to become a British subject so he could reward him. "Ambassador Page told him he had thrown away a peerage, a notion that Hoover dismissed with a grunt."
  • Hoover headed the United States Food Administration created by the Lever Act in 1917. "To “Hooverize” meant to clean one’s plate, endure a meatless meal, or otherwise consume food in an economical matter. He had levied eight hundred penalties for breaches of his directorate’s rules and closed 150 businesses for violations."
  • He was the executive director of American Relief Administration (ARA) "The official mandate of the ARA expired July 1, by which time it had distributed $1.1 billion in food and aid. He secured Wilson’s approval to use his ARA surplus to endow the European Children’s Fund as a new private charity. Over the next five years it would provide clothing, hot meals, and medicine to 15 million children...Keynes, whose pessimism toward the peace settlement had matched Hoover’s, called him “the only man who emerged from the ordeal of Paris with an enhanced reputation.”"
  • He was Commerce secretary for Harding and Coolidge.
  • In 1927 the Mississippi River flooded, "levees would be breached at 140 points in six weeks...six governors, including Murphree, had begged Calvin Coolidge for federal assistance. Specifically, the governors had asked that Herbert Hoover be assigned to lead a federal rescue effort."
  • Hoover was ambivalent about prohibition, but was backed by Dry politicians for his 1928 election. Prohibition was poorly enforced: "states spent six times more upholding fish and game laws than they did on Prohibition."
  • While president, Joel Boone, the White House physician, made him promise to loose weight. "Within the week, Boone had arranged for a collection of the president’s friends and associates to gather every day at 7 a.m. on the White House’s south lawn for a game of their own invention. It called for two to four players a side. It used the rules of tennis with a six-pound medicine ball heaved back and forth over an eight-foot volleyball net. Victory went to the team with the most points when a factory whistle down by the Potomac blew at seven thirty. Eventually they would call the game Hooverball."
  • "Despite the hubbub, the economic impact of Smoot-Hawley was negligible. It moved the average tariff on dutiable imports in the U.S. from already high to slightly higher. The legislation was responsible for a 5 percent decline in American imports, an insignificant amount when dutiable imports represented just 4 percent of GDP in 1929."
  • Early in the great depression Hoover was praised. From 1930 “For the first time in our history,” wrote Keynesian forerunners William Trufant Foster and Waddill Catchings, “a President of the United States is taking aggressive leadership in guiding private business through a crisis.”
  • Prohibition was a big issue in the 1932 election. "The New York firm Houser Associates undertook what appears to have been the first scientific national election poll for either party. Among those defecting, 83.6 percent believed that repeal would be good for the country"
  • I liked this quote from Hoover's memoir: “Democracy,” he later wrote, “is a harsh employer.”
  • Hoover a a sore looser. Never met with FDR after his inauguration. He constantly criticized the popular New Deal. He received votes for the Republican nomination in 1932 & 1936.
  • He was influencential in his eighties. He spoke at every Republican convention from 1928 till 1960. After the 1960 election "he and Joe Kennedy brokered a postelection public peacemaking between the two combatants over the holidays in Palm Beach. So great was JFK’s regard for Hoover that he repeatedly tried to put him back in harness, first as honorary chair of the national advisory council for the new Peace Corps, and later as honorary chair of the advisory committee for the Food for Peace program run by White House aide George McGovern."

Sunday, October 14, 2018

Review of "The Devil's Delusion"

Subtitled "Atheism and Its Scientific Pretensions" by David Berlinski.

This book is the definition of confirming by bias. Berlinski is arrogant, sarcastic, erudite and contrarian. I like his writing style and the book is only 225 pages. This book is not for everyone and is down right insulting to some. The preface to the second edition sums up who his intended audience is: "a great many men and women have a dull, hurt, angry sense of being oppressed by the sciences...They are right to feel this way. I have written this book for them."

In the first chapter, "No Gods Before Me", Berlinski makes a cleaver twist on the commandment to reference the belief in what I would call scientism summed up nicely in this quote: "Confident assertions by scientist that in the privacy of their chambers they have demonstrated that God does not exist have nothing to do with science, and even less to do with God's existence."

The next chapter, "Nights of Doubt", he explores the history of disbelief. "For scientists persuaded that there is no God, there is no finer pleasure than recounting the history of religious brutality and persecution...Nonetheless, there is this awkward fact: the 20th century was not an age of faith, and it was awful. Lenin, Stalin, Hitler, Mao, and Pol Pot will never be counted among the religious leaders of mankind."

In "Horse Do Not Fly", Berlinski goes deeper into the faith exhibited in modern science. From a letter by Richard Thomas talking about baffling math results in recent history, "To a mathematician, these things cannot be a coincidence, they must come from a higher reason. And that reason is the assumption that this big mathematical theory describes nature." Berlinski then writes a funny twist from the Bible, "Western science is above all the substance of things hoped for, the evidence of things not seen."

In "The Case", he introduces one of his clever tricks, fake dialog. "The question: What causes the universe? The answer: Something." He then introduces Thomas Aquinas, whom Berlinski calls the "largest intellectual personality of the thirteenth century." I have heard of Aquinas, but was unaware of his influence. One of Aquinas' arguments, his Summa Theologica contains 38 treatises and 612 separate questions, was "causes in nature cannot form an infinite series." He ends with a quote from astrophysicist Christoper Isham, "Perhaps the best argument in favor of the thesis that the Big Bag supports theism, is the obvious unease with which it is greeted by some atheist physicists."

The next chapter, "The Reason", deals with why the universe exists. Berlinski does a good job of explaining the history of quantum physics. Then he has the following, which I find hilarious:
A Catholic catechism of Quantum Cosmology
Q: From what did our universe evolve?
A: Our universe evolved from a much smaller, much emptier mini-universe. You may think of it as an egg.
Q: What was the smaller, emptier universe like?
A: It was four-dimensional sphere with nothing much inside it. You may think of that as weird.
Q: How can a sphere has four dimensions?
A: A sphere may have four dimensions if it has one more dimension than a three-dimensional sphere. You may think of this as obvious.
Q: Does the smaller, emptier universe have a name?
A: The smaller, emptier universe is called a de Sitter universe. You may think of that as about time someone paid attention to de Sitter.
Q: Is there anything else I should know about the smaller, emptier universe?
A: Yes. It represents a solution to Einstein's field equations. You may think of that a good thing.
Q: Where was that smaller, emptier universe or egg?
A: It was in the place where space as we know it did not exist. You may think of it as a sac.
Q: When was it there? A: It was there at the time when time as we know it did not exist. You make think of this as a mystery
Q: Where did the egg come from? A: The egg did not actually come from anywhere. You may think of this as astonishing.
Q: If the egg did not come from anywhere, how did it get there? A: The egg got there because the wave function of the universe said it was probable. You may think of this as a done deal.
Q: How did our universe evolve from an egg? A: It evolved by inflating itself up from its sac to become the universe in which we now find ourselves. You may think of this as one of those things.
The sixth chapter, "A Put-up Job", is probably my favorite. In describing the fact that many constants need to be just where they are for life to exist, he quotes the physicists Paul Davies, "Scientist are slowly waking up to an inconvenient truth - the universe looks suspiciously like a fix." Berlinski then does a decent job of explaining the history of string theory and does his best to make fun of it. He quotes a good chunk from Leonard Susskind, "If, for some unforeseen reason, the landscape turns out to be inconsistent...I am pretty sure physicists will go on searching for natural explanations of the world...One might argue that the hope that a mathematically unique solution will emerge is as faith-based as ID." ID being intelligent design.

The next two chapters were not too interesting to me. In "A Curious Proof That God Does Not Exist", Berlinski goes on a rant against Dawkins. Chapter 8, Our Inner Ape, a Darling and the Human Mind", he goes after determinism, evolutionary psychology and Steven Pinker.

Next up, "Miracles in Our Time", Berlinski goes after the grand poobah, Darwin, his disciples (i.e. Hitchens) and his theory of evolution.He quotes an unnamed Nobel laureate, "Darwin? That's just the party line." Something interesting and maybe worth looking into is Euguen Koonin, "Major transitions in biological evolution, show the same pattern of sudden emergence of diverse forms at a new level of complexity...No intermediate 'grades' or intermediate forms between different types are detectable." Another interesting theory is the neutral theory by Motoo Kimura, "the great majority of evolutionary changes at he molecular level, are caused not by Darwinian selection, but by random drift of selectively neutral mutations."

The book ends with "The Cardinal and His Cathedral", an attempt to draw parallels to Cardinal Bellarmine and Galileo. I think he should have ended with this, "If science of the twentieth century has demonstrated anything, it is that there are limits of what we can know."

Friday, December 2, 2016

Mike Polen's Reviews > Messy: The Power of Disorder to Transform Our Lives

Messy: The Power of Disorder to Transform Our LivesMessy: The Power of Disorder to Transform Our Lives by Tim Harford
My rating: 5 of 5 stars

This book entertained, educated and inspired me. It is relatively short (265 pages) and has a simple premise: openness and adaptability are inherently messy and that is a good thing. The book is full of interesting stories I fully enjoyed. The Introduction starts with the the background to the Köln Concert by the pianist Keith Jarrett. Wikipedia says it "went on to become the best-selling solo album in jazz history, and the all-time best-selling piano album" and that's not the interesting part. Each of the nine chapters has a one word title, BTW this makes for fun word combos at the top of each page (e.g. Messy Winning), which tell a series of stories wrapped around the main point to tell a sub point.

The chapters (Creativity, Collaboration, Workplaces, Improvisation, Winning, Incentives, Automation, Resilience, and Life) have a wide range of anecdotes. The ones that spoke to me covered the founding of the SAS, King's "Normalcy, Never Again" speech that ended with the best Improvisation ever, Brian Eno's crazy,musical genius, Muzafer Sherif's Robbers Cave Experiments, MIT's building 20, John Boyd's OODA loop, Earl Wiener's laws especially "Digital devices tune out small errors while creating opportunities for large errors.", Diederik Stapel's fraud, Flight 447 and Monderman's "Squareabout". This book gave me hope that the current craziness of data-driven, top-down, mega-management has a kink that hopefully will be cracked by passionate, messy pioneers.


View all my reviews

Sunday, August 28, 2011

Review of "The Genius in All of Us"

Subtitled "Why everything you've been told about genetics, talent, and IQ is wrong" by David Shenk.

I first saw this book at a swim meet. A parent sharing at our table was reading it and I dismissed it based on the cover main title alone. Through a discussion with the reader's wife she asked me "Are you judging a book by it's cover." My prejudice was exposed therefore I was determined to read it if only for penance.

I recommend this book especially since it is only 134 pages (with 168 pages of notes and bibliography). It starts with a story about Ted Williams that shows the dedication it took for him to become the best hitter in baseball. This theme is repeated many times.The author introduces you to the developmental systems theorists concept of GxE (genes times environment). The book attempts to debunk the myth that your abilities (and to some degree who you are) are mainly determined by genes. GxE will admit genes play a role, but that the choices one makes have a far greater impact than genes.

He then beats up Lewis Terman, but anyone who has read "Outliers" already knows the punch line: you can't predict the future based on some test, specifically one as limited as IQ. He lists some environmental triggers that I like:
  • Speaking to children early and often
  • Reading early an often
  • Nurturance and encouragement
  • Setting high expectations
  • Embracing failure
  • Encouraging a "growth mindset"
Next he introduces us to the with the work of Dr. K. Anders Ericcson. Ericsson and William Chase did studies on improving memory of "average" students. They concluded "With practice there is seemingly no limit to memory performance." From there he articulates the various myths people have spouted over the years about genius; focusing on Mozart (BTW his father was obsessed with making him the greatest composer in Europe as he had failed). He provides these themes for greatness:
    • Practice changes your body
    • Skills are specific
    • The brain drives the brawn
    • Practice style is crucial
    • Short-term intensity cannot replace long-term commitment
    Then he dives into a famous twin study (from 1981) that "proved scientifically" that genes determine 60% of intelligence and personality; 40-66% of motor skills and 21% of creativity. In case you haven't already guessed the author rips holes in this study and explains the results using GxE theory. Next he lists some emergent ideas from genetic testing of  high performers (Kenya long distance runners, Navy SEALS, Jamaican sprinters, etc):
    1. Despite appearance to the contrary, racial and ethical groups are NOT genetically discrete
    2. Genes don't directly cause traits; they only influence the system
    Guiding principles suggested by author for people who wish to be great:
    • Find your motivation
    • Be your own toughest critic
    • Beware the dark side (bitterness and blame)
    • Identify your limitations; then ignore them
    • Delay gratification and resist contentedness
    • Have heroes
    • Find a mentor
    More recommendations by the author on how to ruin (or inspire) a kid:
    1. Believe
    2. Support, don't smother
    3. Pace and persist
    4. Embrace failure
    His final point is: "Lifestyle can alter heredity."

    I admit I was surprised how much I didn't know about recent theory. I knew IQ tests were bogus. I had read Gladwell's "Outliers" and knew of his 10,000 rule, but I still held on to this idea that my genes had a lot to due to who I was. Reading this book didn't change my outlook on life, but it did change some of the dialogue around it.

    Saturday, July 9, 2011

    Lean 101

    Lean is a philosophy derived from manufacturing (see Lean.org for more details) that has made inroads into many things, including software development. When people try to adopt it they tend to focus on the techniques and often miss the big picture. When faced with a task, how you think about it will determine how you attempt to perform it.

    Take laundry for example. The most common method is to first sort all the dirty laundry into piles of like colors. Then wash them one at a time and as they wash throw them in the drier. As the dry hang and fold and/or make piles for each person to take care of their own. This divide and conquer approach is usually tool #1 in our tool-belt.

    A lean approach would start at a different place. Lean would start on value. Why do we do laundry? What's the end goal? For me it is clean clothes in my closet. If I could have elves do it for me while I slept I would be satisfied. Since I can't seem to find any nocturnal elves willing to work for free I am stuck doing it. I start with four laundry baskets (and some floors) filled with dirty clothes and I need a process for getting these clothes cleaned and put in the appropriate drawers and/or closets. The clothes need to be cleaned in the washing machine, dried (or laid out for those pesky clothes) and folded/hung in the correct location.

    Lean tells us to pull value, instead of pushing it. What does that mean? Pushing can be thought of as focusing on the sub task. Let's take the first sub task when doing laundry - sorting. Pushing is doing all the sorting before starting a single load. You make sorting the goal before you move to the next task. This can lead to suboptimization. In lean we are trying to maximize value. One tool lean has is to minimize work in process (WIP). WIP isn't value and utilizes resources without providing value. In my domestic example WIP is piles of laundry on the floor. So how do I get laundry done when I don't have pre-made piles to throw in to the washing machine?


    1. Take clothes that can be washed together from the dirty clothes hamper containing the most import clothes (mine) and toss them in the washer. 
    2. When they are done toss them in the dryer.
    3. Go to #1 until all clothes are done

    A problem this approach can run into is when I focus on maximizing the amount of clothes I can stuff in the washer. Doing this is similar to maximizing the output of a machine on a factory floor. When I do this the clean, wet clothes have to wait for the dryer. As I am maximizing the amount of clothes I put in the washer my WIP is bigger than it should be. Kanban (a practice from lean manufacturing) uses WIP limits to prevent this from happening. I simply need to learn the amount I can place in the washer so that the washing (a fixed time on my machine) matches the drying time (a variable time on my fancy dryer). This is the Lean principle of Perfection.

    In software development lean tells us to pull the value. Value is software that is being used by those that paid (at least indirectly) for the software. One common mistake when adopting a lean based software development approach is to force the business customer into breaking cohesive features into bite size ones that are of NO value to the business by themselves. Instead the development team needs to own the break down of features into bite size one and deliver the cohesive feature in a way that the business can use. Sometimes the feature can be delivered piecemeal, but often the feature is not useful until all parts (think CRUD) are done.

    The other mistake is trying to to the entire feature at once. This is comparable to shoving all the clothes in the washer. You need to find the smallest unit that works for your group. In a small group (one-two developers) in can be tackled in extremely small increments (one test at a time in TDD). In larger groups more coordination will be needed. It will be up to each group to find the sweet spot (like how many pants can my drier dry in one wash cycle).

    One thing to keep in mind when adopting a lean approach is there is NO ONE RIGHT WAY. Every situation is different and requires different practices and rules to be optimal. The key is the Perfection principle. Never be satisfied. Always look for ways to make the software better, faster and more valuable to the business. Sometimes you will try ides that cause a step backwards in productivity, but these are a step forward in knowledge. Remember perfection is not achievable, but with lean you should always be seeking it.

    Sunday, June 27, 2010

    Review of "The Shack" by William Young

    I loved this book. It wasn't well written (you are not surprised to find that William is a first time author), but the story and the depth outshines all it's flaws. It is not a easy read. I had to put it down several times as I couldn't take the images in my mind and I cried several times but I laughed even more.

    The story is based around a fictional character, Mack, and his weekend with Elousia (El - semitic for God; ousia ancient Greek for being), Sarayo (Sanskrit for wind), & Jesus. The chapters leading up to the weekend will turn many away as it isn't a pleasant story. Make sure you have a box of tissues in easy reach for chapters 2-4.

    Each chapter has a quote at the head. I liked each one. My favorites are:
    Chapter 4: "Sadness is a wall between two gardens." -Kahlil Gibran
    Chapter 6: "...no matter what God's power may be, the first aspect of God is never that of absolute Master, the Almighty. It is that of of the God who puts himself on our human level and limits himself." -Jacques Ellul
    Chapter 14: "God is a verb" -Buckminster Fuller
    Chapter 18: "Faith never knows where it is being led, But it knows and loves the One who is leading." - Oswald Chambers
    The meat of the book has some great lines as well:
    "Who wants to worship a God who can be fully comprehended...Not much mystery in that."
    "Faith does not grow in the house of certainty."
    "There are a lot of smart people who are able to say a lot of the right things...but they don't know me at all. So really how can their answers be right...?"
    For me this book has take the place of "Mere Christianity" by C.S. Lewis as the best book for an introduction to Christianity. I plan on reading it again.

    Addendum: The reason I read this book was because my father recommended it. He reminded me when we spoke :-)

    Sunday, June 6, 2010

    Measurement 101

    When I got from spring break I noticed that most of my pants were tight and my typically lose pants fit nicely...not a nice feeling! I shouldn't have been surprised I had stopped going to the gym on a consistent basis and I wasn't watching what I ate for long (just the short time it was on my plate :-) The first step was obviously to get back in the habit of going to the gym. After about a week I noticed some pants felt better, but I wasn't happy with the "just try harder" approach. I decided I needed a change in my approach. I got up my courage and took the big step of...getting on a scale. It was not pretty. In fact it was slightly depressing, but I kept doing it every time I was at the gym.

    The point of this post isn't my weight though. It is the about the saying: "If you can't measure it, you can't manage it." I have had an interesting history with measurement. I have always liked numbers. In fact I used to calculate (in my head) the estimated time of arrival (in minutes) to home every time I passed a sign with miles to home. Yes, I know I have issues. When I worked at Motorola they used to publish our software release sigma number. I found out that this number was the number of defects found in the last release divided by the number of lines of count. This was obviously wrong as I could have added NOPs and got that number lower without improving the quality at all. When I consulted with government contractors (almost all where SEI level 3 or higher) I found several measures that were more complicated but in effect similar to Motorola's sigma. When I spoke up about these measures being easily duped and misleading, the response was: what do you suggest we measure instead? Good question...I didn't have an answer. 

    How do you manage if you have no quantitative way of saying you are getting better or worse? The key, I think, is something I was taught my a measurement guru a worked with once (Chris Miller, please forgive me if I butcher this:-). 

    First start with the goal (i.e. improve productivity, quality, waist line). Next find some measures that are good predictors of those goals. Examples: 
    • Goal: medium rare meat - measure: internal temperature as measured by a meat thermometer.
    • Goal: smaller waist line - measure: same scale at the same time of day
    • Goal: software productivity - measure: lines of code (this is worth a whole post, but not this one)
    Be careful not to believe the measures are the goal as this trap will lead to manipulation and a false sense of where you are. Now, look at your process (lots of people use an idealized process...another trap) and see what measures you can capture cheaply. Start capturing (sometimes the historical data is laying around and you can go back in time) and do some simple statistical analysis to see if any of these measures correlate with the goal measures and thus can be your predictive measure. 

    Let me give me an example that most can empathize with. I have a goal of smaller waist line. My goal measure is my weight on the gym scale in the morning (experience has taught me my weight fluctuates widely throughout the day). My predictive measures eluded me until my wife introduced me to SparkPeople (image an intersection between Facebook and Weight Watchers) The web site is fairly painful to use, but the android app is quite good and lets me enter in all the food I eat fairly easily. Now I have a predictive measure that is fairly cheap. Now for the simple statistical analysis.

    We are after correlation coefficient (CORREL in Google Docs Spreadsheet) . Next we square it and display it as a percentage ("The square of the coefficient (or r square) is equal to the percent of the variation in one variable that is related to the variation in the other." from http://www.surveysystem.com/correlation.htm) The smaller the better. In my case it was .1% so I think it's a keeper.

    One trap I fell into, and still do at times, is the old accuracy/precision trap. I have already described this:
    I am sure there is quote out there, but here is my general rule: let the level of precision of a number be based on its accuracy. Accuracy of an estimate is always low so please don't use decimals (precision) If you don't understand, please read this explanation of the difference between precision and accuracy.
    In my case it isn't estimation as much as it math. If you spend hours getting your predictive measure (i.e. calories consumed) you are wasting precious time. Let me give you an example. SparkPeople keeps my calories to 1/10 a calorie, but what if round my calories to the nearest 100....my correlation changes to .02%...yes in actually gets better (its a math trick...given different sets of data it could have gone .08% the other way) but the point is .08% or even .8% isn't worth the time it took to write it. If I round my correlation to the nearest whole percentage they both are 0% or practically perfectly correlated. So don't sweat the small stuff and keep you mind on the goal whether it be fitting into old pants or productivity improvement.