Questions tagged [measurement]

Measurement is the assignment of a value (numeric or otherwise) to an observation.

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Objective measures in Factor Analysis

I am considering developing a questionnaire (to be validated) whose scales could include both self-reported subjective measures and objective measurements. Does it make sense to use factor analysis to ...
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Can ratio data have negative values?

I get the concept of a "true zero" value, but I'm not sure why this implies that there cannot be any negative values—at least that's what most sources say that I found only, with only few ...
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How do I measure the performance of a model when only partial ordering matters?

I have a number of input data points $\{ x_0, x_1, \ldots, x_n \}$ and their corresponding outputs $\{ y_0, y_1, \ldots, y_n \}$. I also have two models $f, g : X \rightarrow Y$ that seek to estimate ...
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How to integrate objective measurement with subjective measurement? [duplicate]

I am building an index to measure Visual Pollution, and I have two sets of data: Subjective data: How satisfied people are (out of 100) Objective data: Number of Waste Bins and other factors (...
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The difference between Index and Indicator

I am investigating the topic of Visual Pollution in my city, and have established some indicators such as Number of Visible Waste Bins and others but now, I am interested in building a single number ...
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How to handle additional measurement uncertainty from non-fixed sensor with Kalman filter?

Most examples I've seen of Kalman filters assume a measurement w.r.t. a global reference frame; i.e. direct measurement of location, and therefore direct measurement of a state. Consider the scenario ...
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Comparing Dissimilar Survey Questions

I am hoping to gain some insight on the most responsible way to fulfill a request at my place of work. I have been asked to show a quantifiable improvement year-over-year, by comparing apples and ...
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Finding most likely permutation

[Hoping that this is the right Stackexchange site; inspired from a true story seen at work] Joe has a measuring instrument and $n$ objects to be measured (say, a scale and $n$ weights). He measures ...
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Statistic for measuring the magnitude of bimodality in a distribution?

Here are some distributions of US political views by industry: After observing their mostly bimodal nature, I would like to measure the degree of bimodality in each of the distributions for the ...
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Controlling for Exam Change in Regression Model?

I am analyzing exam data collected from participants who applied to an academic program. The data was collected from 2014-2018, and applicants only took the exam once when applying to the program (...
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What are the statistical drawbacks of my naive and simple approach to discarding outliers?

I'm trying to measure and compare the performance of some computer programs. The simplest idea that comes to mind is to time, say, 10 runs in a row and present the arithmetic mean of the 10 timings as ...
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Is interval level of measurement the same as grouped data?

When data is grouped into intervals, will this be considered be as measuring data on the interval scale?
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Bootstrapping the time until an event happens

Assume I have some measurements $\{(y_i, t_i)\}^n_{i=1}$, where $y_i$ is a real number (measured quantity) from some unknown random function $y_i = f(x_i)$, $x_i$ are inputs to that function and $t_i$ ...
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(Apparently) Different Definitions of Statistical Independence

I am reading John Mandel's book " The Statitical Analysis of Experimental Data). In it, in Ch 5, p. 52, he describes Statistical Independence of two RVs $X,Y$ in terms of independence in the ...
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Ipsative / constant sum measure in multiple OLS regression

I am conducting a moderated OLS regression where my four moderating variables are measured through a constant-sum scale (i.e., distribute 100 points on the following four dimensions [my moderators]). ...
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how to interpret no change in chi square value in measurement invariance analysis, using lavaan

Currently I am using lavaan R package to do some measurement invariance analyses. One warning that I get confuses me a little bit: ...
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What can I say about possible systematic bias between these two sets of measurements?

I have 6 objects $O$ and for each the quantity $X$ has been measured by two methods $M$. The uncertainty of $M_1$ is determined by others to be 1%, k=2. The uncertainty of $M_2$ is determined by ...
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Intervention analysis

I'm really struggling to figure out how to construct a model here. Basically what I'm trying to measure is if a school endorsing a statement causes that school to change their policies. I have data on ...
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How to Construct an Index

I'm sorry in advance that this question is a little bit broad. I'm trying to create on variable to measure the overall prestige of a university. I'm using data on federal obligation, tuition, as well ...
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How to test if two methods of measurement are consistent?

I am measuring (the same) property of of 20 different objects. To measure this property I have two methods at my disposal. Which statistical test should I use to determine whether these two methods ...
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What does “at least ordinal” mean?

When the assumptions of a statistical test state that "the measurement scale should be at least ordinal", what does that mean?
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Categorical data type

Suppose I send surveys out to students’ parents to assess how often parents seek tutors to help their children with schoolwork. Parents are selected from schools across the country. As part of my ...
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What level of measurement can I use to compare a student's different test scores?

Let's say a student takes multiple different tests. I get a percentage for each of the test scores (the tests have a different amount of multiple choice questions, and the multiple choice questions ...
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Imputing data using covariance?

Suppose I have some samples of sensor data, where each row has ten measurements from various sensors. And suppose I know what the covariances are among these sensor measurements. Are there any ...
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How to interpret hedge's g and how to handle p-value in this context for a sensor measurement/comparison?

It might be that this question has been handled already but there are so many about hedge's g I cannot walk through all of them. Please excuse if it is a duplicated question. I would like to know ...
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Using two sensors instead of one: Statistically meaningful?

We are using resp. manufacturing a certain device which measures, among others, the humidity of liquids. I got asked by a colleague if it makes sense to use two sensors instead of one (which a ...
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Does rounding violate the restrictions of an interval scale?

I'm currently working with questionnaire data from the NASA TLX. It uses a graphical rating scale with 100 equally spaced data points, broken up by 21 ticks, leaving intervals of 5. Its manual (p. 4) ...
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Estimating the actual distance by using a series of measurements in between

An object is moving along a single axis, back and forth. We take $N$ snapshots of the object. For all pairs of snapshot positions $i$ and $j$, we can make signed measurements of distance $x_{i,j} = -...
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What kind of a measurement variable are these?

Can anyone please explain what kind of a measurement variable these are? Facebook Pictures - I feel that these should be nominal but if there is a date stamp on the images, then it would be ordinal. ...
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Determine if clusters of combined values are coincidental

I have a set of measurement results like this (hex numbers): 30AF, 31AE, 30AF, 30AE, 31AE which vary only slightly, there are usually 3-4 distinct values per measurement set of 30 results(could ...
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What are some “nice” properties a “similarity index” should have?

I am reading a book that talks about how to construct a similarity index operating on a probability vector $\mathbf{p}=(p_1,...,p_k)$ to describe how similar its elements are. In my book, indexes of ...
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Measuring true value in an interval accounting for contributions from neighboring intervals

Suppose I have a record of every purchase of food made in 2019 and 2020 and I want to answer the question: how much did I spend on food in March/April/May in those two years (to see how much I'm ...
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multi group comparison

I have the following measured (observable/manifest) variables: two variables capturing two participant behaviours while solving a task two variables that measure the participant's outcomes on that ...
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How many days should I measure a variable to get a good estimate of 'average' behavior?

I have data for individuals, spread over a number of days. My dataset is very large: it covers way more days than what is typically feasible to collect. I want to use this to create a 'benchmark' of ...
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How to compare inter-rater reliability between two time points?

We have two sets of raters judge the same items before and after a training, resulting in an ICC and kappa value for each time point (pre- and post-training). How would you statistically compare pre- ...
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stats question on percentages

I would like to compare the coefficient of variation (percentage) between two groups for statistical significance. Each group is comprised of 15 patients with each patient demonstrating a separate ...
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Please help me with selecting the appropriate test for a measurement

I am a freshman psychology major and have coursework to write scientific papers. I have found a topic that I am interested in and I also have found the journal. I have read the journal but could not ...
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If a false positive rate of α is desired, what is the acceptable range of false positives one would expect from a sample size of n?

For instance, suppose I design a test to have a false positive rate of 5%. I am going to perform this test on what is assumed to be an all negative population. If my sample size was 20, I would expect ...
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Modelling Ball Movement using Delayed Measurements with Known Latency

I am a hobby programmer currently developing an algorithm to combine measurements of a dynamically moving ball position (and velocity) from multiple robots. Each robot measure and calculate the ...
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Can I use anova on values in decibel (logaritmic)?

I'm doing a project where I'm measuring outdoor sound in different spots. I've repeated the measurement 3 times at every spot on different days (with different weather etc). I measure every spot for ...
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Number of observations to study the reproducibility

I'm running an experiment which is about to investigate the influence of gases on the resistance of sensors. Since this is chemistry and gases are experimentally rather hard to handle, I would like to ...
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118 views

Instrument accuracy necessary to distinguish two values

Let's say I want to know the size of some shoes, but the size isn't marked. The real size could be any of [35,36,37...50 cm], and the shoes are made so well that their real size is exactly one of ...
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Comparison between two measurement devices

I have two measurement devices accelerometer A and B. The measurement is the step time of a person walking in a corridor. A is the gold standard. I want to check the validity and reliability of B. how ...
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1k views

How can I know if two distributions have the same mean and standard deviation?

I have some cells which fluorescence and I can detect their fluorescence. So for each cell I get a number N that says how much light it emitted. I also have two ...
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How do I propagate asymmetric error/confidence intervals? [closed]

Assume that I have two measurements with asymmetric error, $X^a_b$ and $Y^c_d$, and I want to find $Z^e_f = X^a_b + Y^c_d$. How do I find Z? The type of answer I'm looking for is of the form : $e = ...
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Is median or mean more accurate for technical replicates of assay (small n)?

If I want to improve the precision of the results of an assay by averaging a few repeat measurements of each sample, when the random error is generally normally distributed but occasional outliers ...
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Ratio Measurement Scale and Absolute Zero

Levels of measurement are: Nominal, ordinal, interval and ratio. What happens when the absolute zero of a data set using the ratio scale is a negative number? I.E when the absolute zero is -25,000? ...
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Modeling background noise with a half normal distribution

I'm working with radiation measurement data and have background noise data with $(\mu, \sigma)$ < 1 and all background measurement values >= 0. If I wanted to approximate/model this noise, would a ...
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How to compare two, time based, measurements of the same object

I have 2 rounds of measurements from a set of 10 capacitors. The measurements are with respect to frequency and are all measured at the same 200 frequencies between 1 kHz and 5 MHz. The data is not ...
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Measured data not normalized - but should it be?

I'm analyzing some data at the moment and I just stumbled over the situation that a part of itseems to be not normalized. Background: Several gas sensors were measured and the value of a resistor is ...

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