Questions tagged [statistics]
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47 questions
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Tolerance stacking - potential statistical distributions
Is there a reason to believe that for given symmetric tolerances (e.g., 6, modern metal milling techniques result in a non-Gaussian distribution? It makes some sense to me that the distribution would ...
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1
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How to determine the effect of manufacturing variability on assembly of items
Any help is appreciated. Below are some details
The product has around 20 different components (including ones manufactured to spec, fasteners, off the shelf, consumables, etc.)
Lets assume the ...
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Costs of fatigue damage - need some statistical data / USA, Europe, Asia
I am looking for (pretty current/actual) statistical data related with Fatigue damage in machines, Annual fatigue costs in industry (for example with refference to Gross Domestic Product), time ...
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How do I find a target standard deviation for my own testing given a confidence level, a mean, and bounds for the interval?
I'm working on a project involving a couple of material dispensers, and the customer we're designing them for has asked us to keep the output of the dispensers within a set range 95% of the time. I'm ...
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How to Determine a Valid Relationship Equation Between Two Finite Datasets -- Python, Matlab or Other [closed]
I struggled to find a clear solution online so I'm resorting to asking a fresh question.
I have two finite datasets (call them 40x1 vectors) that are equal in length and generate non-linear curves, ...
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2
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34
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Trendline estimation
Let's say you had a scatter plot with lap times on the y axis and tyre pressure on the x-axis from an experiment where your dependent variable is lap time and your independent variable is tyre ...
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2
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151
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System identification of a simple motor with only position measurements
(Cross-posting from statistics stackexchange)
Say we have a permanent-magnet DC motor that roughly obeys the system equation
$$\ddot{x}(t) = \alpha \dot{x}(t) + \beta u(t) + \gamma $$
where $x(t)$ is ...
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How to add a Gaussian noise signal with zero-mean in a given data set?
I have a real-time velocity measurement data set in a excel (.xlsx) file. I want to add the Gaussian noise signal with zero mean in this real-time data to create three set of pseudo measurements. ...
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177
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Relationship and interpretation of "discrete" and "continuous" covariance matrices in Kalman Filtering
I am quite confused about the interpretations/implementation of the system and measurement noise covariance matrices for the continuous and discrete time Kalman Filter. What I want is to initialize ...
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How much energy do all the world's emails use?
I have heard high level statistics and headlines around
blockchain uses more energy than the Netherlands
I am interested to compare this quantitatively to other utilities, for example email and ...
- 111
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3
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696
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Usage of the three-sigma limits in calculating minimum force
I have carried out 10 cantilever sample tests that provide a braking force as follows (in kN):
22.1, 20.98, 21.03, 20.7, 21.03, 21.09, 20.98, 21.08, 21.24, 21.19
The goal is to recommend the worst ...
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Covariance of an uncertain vector going through an uncertain rotation
I have a vector $\omega$ and it associated covariance, a rotation $\mathbf R$ and its associated covariance. What is the covariance of $\mathbf R \cdot \omega$ ?
More rigorously:
I have an estimation ...
2
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1
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157
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Compare Genetic Algorithms and Markov Chain Monte Carlo in their statistical properties in parameter estimation task
I am using GA and MCMC for estimating the parameters of a transfer function. GA returns results that each parameter has one value when minimizing the error function, and MCMC returns the whole chain ...
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When NOT to use Bessel's Correction for Standard Deviation
I can not find a clear explanation for when NOT to use Bessel's correction and use N instead of N-1. As I understand it, Bessel's correction would apply to things such as clinical trials, sampling ...
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Talking in terms of 6 sigma, why 4 ppm would be very costlier than 1 ppm (part per milion)?
In industrial manufacturing lines, there is a a limit on the number of discarded parts per million.I need to have a sense about this, e.g. How different is 4 ppm from 1 ppm and how much does it ...
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accurate measurements with less accurate tools
Is there a good way to systematically increase the accuracy and precision of a measuring tool using only mathematical means? For example, average 10 measurements from the same tool can create a ...
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Can you convert a histogram of linear separation of lines into a distribution (histogram, PDF, PMF) of their lengths?
I have an image of lines (they're actually crystal defects viewed through an SEM)
What I'm really after is a histogram of line lengths, but as can be seen from the above micrograph, most lines exit ...
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91
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How to sample Mean-Time-To Failure values from a Weibull Distribution with shape 1.5?
I have a mean time to failure (MTTF) recorded from 100 systems which is 6.5 years. The shape parameter of my component is given with k = 1.3 (based on a list the from literature).
Now I want to ...
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2
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60
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How to find raw data sets for engineering?
For one of my courses the teachers asked me to find two samples of 30 or queries of data, and I was thinking on how I could begin to search it?
Most of the scientific articles that i looked for ...
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Must MSA (Measurement System Analysis) be re-performed after annual instrument calibration?
I'm working in an automotive company that must follow IATF (International Automotive Task Force) requirements.
I administrate a test-bench that performs RF (radio frequency) tests using an ...
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1
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180
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What measurement accuracy/precision is required to detect a 10% relative change in the measured quantity
I'm trying to design a measurement system, the primary objective of which is to reliably detect a 10% change in the the volume of fluid flowing through a pipe.
I'm struggling to come up with a ...
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How can I calculate uncertainty based on measurements from multiple separate runs?
I am using standard test blocks to find the uncertainty of a supermicrometer, which is capable of measuring down to 1/10 of a micron. The issue is that it measures the EXACT same length within a run ...
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Double interpolation for a large set of data in Excel [closed]
How do you do double interpolation for a large set of data in Excel?
The user is required to input an x value and y value then the program has to find the points and do interpolation if necessary. ...
user15793
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1
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326
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Find spring constant of frame structure
I would like to calculate the spring constant of a frame structure.
I thought that I could do it like this:
I apply a point force on the structure:
Then I calculate the displacement at that same ...
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1
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333
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What is the best graph type to show a comparison value between two cases?
In that graph, I want to show the two values and the error percentage from the comparison between two values. I am using microsoft excel.
can anyone give me any idea which best graph for this case?
...
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58
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How to find all the parameters in weight vector in Levenberg-Marquardt Algorithm?
I already had a data for corroded thickness distribution (in matrix form) for corroded surface model in Abaqus with mesh size 5 cm
I want to create thickness distribution with bigger mesh size (e.g 50 ...
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1
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124
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What does (a) the input of the activation function mean?
I am not very good at understanding the ANN theory, but please if anyone can explain me about what does (a) as input of the activation function mean?
and how to get this value?
Thank you
- 187
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1
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215
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How do I include statistical significant index in bar chart in excel?
I want to have a star dot above each bar chart. I don't know how to present that index. Please anyone help me to resolve this problem,
- 187
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150
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DOE to optimize a chemical reaction with impurity forming in series
This question contains chemistry, but the main focus is DOE design--hence posting on the engineering stack exchange.
The problem is a chemical reaction:
A + B -> Product
Product + B -> Impurity
The ...
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2
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411
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Moments of inertia, rods mechanism
I need some assistance understanding moments of inertia. I am doing some review for an upcoming exam, however I am slightly stumped by this question. I have already tried googling "moments of inertia" ...
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268
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Why Taylor's microscale gives us information about the smallest scales of the flow?
So I understand the principles of two-point time correlations (covariance) and how you can just normalise that to get the autocorrelation. I also understand the integral time scale which is quite ...
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Choosing significant figures when dealing with a wide range of values
In a calculation I have received a number of values in the range $1e4-1e6$. Now I would like to display the values with 3 significant figures according to the rules of using significant figures. But ...
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How do I update an individual control chart?
I'm finding myself using control charts and I'm unclear on a very basic point. I've read page after page of texts, but they all focus on how to make the initial chart rather than walking you through ...
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3
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Guidelines to develop quality engineering training content and select a trainer
Our organization has recognized the need to improve quality of both incoming material and outgoing products. Our products are primarily electrical/electronic but mechanical components are an integral ...
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27
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Pearson correlation of neural responses with it's linear estimation
I am trying to anderstand the following fact from this article (page 13):
How can single neurons predict behavior
Suppose I have a linear estimation of a stimulus:
$ \hat{s} = \mathbf{w}^T(\mathbf{r} ...
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3
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How do you determine the accuracy of a measurement device?
Lets say you have a measurement device of which you do not know the accuracy, and a reference measurement device. Both measure a variable $x$. The range of interest is $x_0<x < x_1$. How do you ...
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1
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180
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Statistical approach to defect detection and prioritization
My company has over 100k communication devices deployed. We collect failure information from the devices. We have two type of data failure count per hour for each device and we use that to calculate ...
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3
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How do I properly compute mean time to failure?
I have a product of which we have shipped something like 500 units over the last five years. This product is not intended to be user serviceable; a failure of any component results in the unit being ...
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4
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1
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How to display data with three degrees of freedom on a chart?
I have a collection of data obtained from calculations and I want to display it on a chart or whiz-wheel or similar, to be used "in the field" as a low-tech solution, since no computer will be ...
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5
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How to identify low quality electronic components early?
Our component sourcing organization purchases large amount of electronic components from suppliers. I believe this is through a bid process. Engineering provides the sourcing organization ...
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4
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438
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How to compare utilization rates?
I have the utilization rates of several machines for each week over a year. These differ per week because of the occurrence of machine failures and changes of orders. Meaning that one week a machine ...
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1
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How to determine if an engineering process is stable and capable?
Mostly interested in understanding how engineers determine if an engineering process is stable and capable, particular in design for manufacturing (DFM) frame work for components. Some example ...
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Question about "uncertainty"
I'm a bit confused about all the different "definitions" of uncertainty?
One can calculate "uncertainty" of a single measurement by simply checking how accurate the tool that is being used to do the ...
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3
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How can the vendor be approved/disapproved based on validation test data?
The power requirement for a sub system is 5V +/- 10% @ 1A of current. A RFQ was issued and a prospect vendor was selected. A first article of inspection (FAIR) has been submitted which includes 15 ...
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1
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How can Pareto Analysis help solve engineering problems?
Attach is a Pareto Diagram with Number of Defects in Y-axis vs Causes in X-axis for an engine overheating problem. How can this Pareto diagram help an engineer solve the engine overheating problem?
...
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3
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1
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Estimating maximum lift or strength
Weight lifters will use the term "one rep maximum" in order to refer to the maximum amount of weight that they can lift one time. The one rep max is often used as a proxy for how strong someone is (...
user16
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3
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How does measurement uncertainty combine with tolerances?
Given a tolerance within which your workpiece should be manufactured, say some length should be $10\pm1$mm. If you determine that your uncertainty in measuring this length is $0.2$mm (at 95%). How ...
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