Estimate Definition and 375 Threads

Estimation (or estimating) is the process of finding an estimate, or approximation, which is a value that is usable for some purpose even if input data may be incomplete, uncertain, or unstable. The value is nonetheless usable because it is derived from the best information available. Typically, estimation involves "using the value of a statistic derived from a sample to estimate the value of a corresponding population parameter". The sample provides information that can be projected, through various formal or informal processes, to determine a range most likely to describe the missing information. An estimate that turns out to be incorrect will be an overestimate if the estimate exceeded the actual result, and an underestimate if the estimate fell short of the actual result.

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  1. S

    Estimate the voltage you need with this appartus to ionize the atom

    A hydrogen atom (with Bohr radius of half an angstrom) is situated between 2 metal places 1 mm apart which are connected topoosite terminals of a 500 V battery. What fraction of the atomic radius does the separation distance d amount to, roughly? Estimate the voltage you need with this...
  2. wolram

    Revisiting Dark Matter Estimates in Axially Symmetric Galaxies

    http://arxiv.org/abs/astro-ph/0602519 Authors: H. Balasin, D. Grumiller Comments: 11 pages revtex4, 4 eps figures Report-no: LU-ITP 2006/002 Exact stationary axially symmetric solutions of the 4D Einstein equations with co-rotating pressureless perfect fluid sources are studied. This is of...
  3. D

    Condition number (or estimate) of a very large matrix

    Hello, I am working on an integral-equation problem in the field of electromagnetics, which gives me a very large linear system that needs to be solved. I use a fairly recent method for this, namely the fast multipole method, which allows me to calculate a matrix-vector product in a fast way...
  4. D

    Rough Estimate about electric light bulb

    Well the question asked us to make a rough estimate of the temperature of the filament in an ordinary electric light bulb which emits white light. And if it has radiated power of 100 W, make a rough estimate of the surface area of filament. Well, the thing is how u make a rough estimation on...
  5. L

    Indirect ways to estimate latent heat of fusion?

    Hello. Often high temperature data are not available. I am missing the melting heat of many coumpounds. However, rather precise binary phase diagrams are available. (my examples deal with silicates, say CaO-SiO2 for example, http://www.npl.co.uk/mtdata/demo/dgox1.html) I would like to...
  6. M

    Estimate time to reach steady state

    I have some first order differential equations. I have found the steady state response for each equation. However, now I need to estimate how long it will take to reach steady state. Can anyone tell me the formula for that or get me started on how i go about doing this. I'm not finding...
  7. K

    Estimate the number of red fishes in the pond

    hi all! I have the following problem (in reality I study objects which may be perfectly described by "fishes" as below): Fishes in the pond: There are N fishes (x of blue color and y of red color) in the pond. N>>10^5, x+y=N, x>>y Each fish has a weight w - positive numerical value...
  8. B

    How can I estimate the motion of Pluto using telescope and camera observations?

    Hi guys, I've been having trouble with this problem and would appreciate just some direction to assist me. I have to estimate the motion of Pluto in "/hour from observations given that the telescope is a 14inch f/11 with an AP7 CCD camera with pixels 24microns on a side. Now we have two...
  9. J

    Does the Shape and Material Density Affect Capacitance in Homemade Capacitors?

    Hi, My question: A homemade capacitor is assembled by placing two 9-in pie pans 5cm apart and connecting them to the opposite terminals of 9-V batter. Estimate the capacitance? I know that to get the capacitance, you can use C=Q/V or C=keA/d. Do I need to find the area of the two pie pans...
  10. A

    How Accurate is the Fish Population Estimate in the Lake?

    Researchers of a department of engineering of fish are studying the fish of a lake. In the first phase of the work they collect 100 fish, place labels in all they and they return them to the lake. One week later them they come back to the lake, they collect more 100 fish and they observe that 7...
  11. S

    Using the Binomial Theorem, find the first 5 terms in the expansion and estimate

    Okay, well, perhaps I am already done, perhaps not. This is why I seek your wisdom :) If you are asked to find the first 5 terms of the expansion (1 + 0.07)^9 using the Binomial Theorem, and then asked to use these terms to estimate the value of 1.07^9 what would you put? I added the 5...
  12. P

    New estimate of effect of methane on climate

    I need to read through this a few more times before I really "get it" but it will be of general interest. After one read-through, it looks like the effects of methane on climate have been underestimated in the past because this gas was measured in the atmosphere after it has mixed with other...
  13. A

    Comparing Sample Means with Pooled Variance Estimate

    Suppose you are conducting a hypothesis test to compare two sample means from independent samples, with the variance unknown, but you know it is the same for both populations. Then you use the pooled estimate of the variance given by [ (n1 - 1)s1^2 + (n2-1)s2^2 ] / (n1+n2-2) I was just...
  14. C

    Estimate the potential of the cloud relative to the ground

    Hello! here is one question which I still donno how to solve: A thunder cloud with a large flat square base measuring 3000m x 3000m passes over an area on level ground. Assuming the cloud carries a total charge of 40C which is spread evenly over its base and is at a height of 0.5 km above the...
  15. P

    Estimate the area under the graph of f(x) =x^2 + 4x from x=1 to x=9

    Estimate the area under the graph of f(x) =x^2 + 4x from x=1 to x=9 using 4 approximating rectangles and left endpoints. first i had to find delta x, so i did 9-1/4 = 2 which means x0 = 0, x1 = 2, x2= 4, x3=6 (since I'm using left endpoints, i include x0) after that, i just plug it in...
  16. C

    Use differentials to estimate the maximum possible error

    Four positive numbers, each less than 50, are rounded to the first decimal place and then multiplied together. Use differentials to estimate the maximum possible error in the computed product that might result from the rounding. I took f(w,x,y,z) = wxzy and then you set df=xzy(dw)+wzy(dx) etc...
  17. W

    Estimate how fast he should be moving

    Kinematics Problem. How do I get T to solve for V(i). PLEASE HELP 9.Superman is supposed to leap tall buildings in a single bound. Suppose that he obeys the normal laws of physics in this feat. Estimate how fast he should be moving when he leaves the ground so that he just clears the top of...
  18. P

    Estimate takeoff speed of aircraft

    Francesca, who likes physics experiments, dangles her watch from a thin piece of string while the jetliner she is in takes off from Dulles Airport. (see pic. attached) She notices that the string makes an angle of 20° with respect to the vertical while the aircraft accelerates for takeoff, which...
  19. marcus

    How do you estimate the temperature 20 feet belowground?

    it is nice and quiet down here in the basement
  20. W

    Gravitron Size Estimate and Higgs Boson Explained

    What is the estimate of the gravitron size and can someone explain why it must be spin 2 also what is the higgs boson it is expected to be massive, electrically neutral, and spinless. why. Cheers Woody
  21. R

    Ray's Estimate of Concorde's Descent Time

    Does anybody have a reasonable estimate of the following, If the Concorde was flying at 6000 ft at velocity of sound ,and it's engines cut out , how long would it take to reach the ground doing the best it could to delay the inevitable ? I've seen answers ranging from <1min to > 7 mins . Ray.
  22. K

    Why Multiply Carbon Isotope Mass Numbers by 1.67x10^-27 kg?

    Here's a verbatim section of the problem: " The source contains carbon isotopes of mass numbers 12, 13, 14 from a long-dead piece of a tree. (To estimate atomic masses, multiply by 1.67x10^-27kg). " My question is isn't the 12, 13, & 14 in the atomic mass units already (Carbon-12 has an amu...
  23. J

    What equation would be used to estimate the temperature?

    Can someone help me get started on this question?: In a Diesel engine, atmospheric air is quickly compressed to about 1/20 of its original volume. Estimate the temperature of the air after compresion and explain why a Diesel engine does not require spark plugs. What equation would be...
  24. Ivan Seeking

    What's your estimate of the other Drake equation?

    The other thread asks about life in the universe. How about the [correct application of Drake's equation] number of planets in the galaxy that support intelligent life?
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