approximation
(noun)
An imprecise solution or result that is adequate for a defined purpose.
Examples of approximation in the following topics:
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Linear Approximation
- A linear approximation is an approximation of a general function using a linear function.
- In mathematics, a linear approximation is an approximation of a general function using a linear function (more precisely, an affine function).
- Linear approximations are widely used to solve (or approximate solutions to) equations.
- Linear approximation is achieved by using Taylor's theorem to approximate the value of a function at a point.
- If $f$ is concave-up, the approximation will be an underestimate.
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The normal approximation breaks down on small intervals
- Caution: The normal approximation may fail on small intervals The normal approximation to the binomial distribution tends to perform poorly when estimating the probability of a small range of counts, even when the conditions are met.
- With such a large sample, we might be tempted to apply the normal approximation and use the range 69 to 71.
- However, we would find that the binomial solution and the normal approximation notably differ:
- TIP: Improving the accuracy of the normal approximation to the binomial distribution
- The tip to add extra area when applying the normal approximation is most often useful when examining a range of observations.
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Approximate Integration
- Here, we will study a very simple approximation technique, called a trapezoidal rule.
- The trapezoidal rule works by approximating the region under the graph of the function $f(x)$ as a trapezoid and calculating its area.
- Although the method can adopt a nonuniform grid as well, this example used a uniform grid for the the approximation.
- The function $f(x)$ (in blue) is approximated by a linear function (in red).
- Use the trapezoidal rule to approximate the value of a definite integral
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Introduction to evaluating the normal approximation
- Many processes can be well approximated by the normal distribution.
- While using a normal model can be extremely convenient and helpful, it is important to remember normality is always an approximation.
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Conclusion
- Many distributions in real life can be approximated using normal distribution.
- If the graph is approximately bell-shaped and symmetric about the mean, you can usually assume normality.
- The data are plotted against a theoretical normal distribution in such a way that the points form an approximate straight line .
- We study the normal distribution extensively because many things in real life closely approximate the normal distribution, including:
- The data points do not deviate far from the straight line, so we can assume the distribution is approximately normal.
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Normal Approximation to the Binomial
- This section shows how to compute these approximations.
- The area in green in Figure 1 is an approximation of the probability of obtaining 8 heads.
- For these parameters, the approximation is very accurate.
- The accuracy of the approximation depends on the values of N and π.
- Approximating the probability of 8 heads with the normal distribution
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Optional Collaborative Classroom Activity
- Construct an approximate 95% confidence interval for the true mean number of meals students eat out each week.
- Construct the interval We say we are approximately 95% confident that the true average number of meals that students eat out in a week is between __________ and ___________.We say we are approximately 95% confident that the true average number of meals that students eat out in a week is between __________ and ___________.
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Calculating a Normal Approximation
- In this atom, we provide an example on how to compute a normal approximation for a binomial distribution.
- The following is an example on how to compute a normal approximation for a binomial distribution.
- The area in green in the figure is an approximation of the probability of obtaining 8 heads.
- For these parameters, the approximation is very accurate.
- Approximation for the probability of 8 heads with the normal distribution.
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Evaluating the Normal approximation exercises
- The superimposed normal curve approximates the distribution pretty well.
- The data appear to be reasonably approximated by the normal distribution.
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Newton's Method
- Newton's Method is a method for finding successively better approximations to the roots (or zeroes) of a real-valued function.
- In numerical analysis, Newton's method (also known as the Newton–Raphson method), named after Isaac Newton and Joseph Raphson, is a method for finding successively better approximations to the roots (or zeroes) of a real-valued function.
- Provided the function satisfies all the assumptions made in the derivation of the formula, a better approximation x1 is x0 - f(x0) / f'(x0).
- This $x$-intercept will typically be a better approximation to the function's root than the original guess, and the method can be iterated.
- We see that $x_{n+1}$ is a better approximation than $x_n$ for the root $x$ of the function $f$.