Questions tagged [measurement]
Measurement is the assignment of a value (numeric or otherwise) to an observation.
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Normalised versus true racing times as DV for a learning experiment?
I have a question about using ratios as variables in alpine ski racing research. We want to compare skiers' performance on different days, but snow conditions affect the results. To address this, we ...
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Best way of determining how unique an inspector's ratings are compared to the average inspector
Noob question.
I have a full population of every inspector rating for all items being rated. Each inspector has inspected a subset of the items and given them a rating, but different inspectors have ...
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Adding a confidence interval to deal with noisy measurements
I have a formula and I am not sure how the author of this paper got to that formula. Im working on an algorithm that can filter out ground points from a Point cloud. The author describes the following ...
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How valid is the use of bootstrapping in my case?
I am currently working on the analysis of measurement data and have the problem of obvious non-normal data. Since most methods I want to use require normality (especially statistical process control ...
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Is ceiling effect mitigated by standardisation, renorming or combining with other indicators?
I have a psychological test that consist of a set of binary items. It has a noticeable ceiling effect in the sum scores (essentially, a majority of participants get most items correct).
I also see ...
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BMI is calculated from two other measurements, so does it need adjusting for multiple comparisons?
If BMI is calculated from measures of patient height as well has weight, do statistical tests and resulting p values around BMI changes need adjusting for multiple comparisons? I.e. Two tests were ...
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Very Basic Question - Propagation of Error and Fold Changes in Medicine
Say you have measured three conditions (x, y, and z) together and at three separate times (three replicates). These raw values are normally distributed and in a linear space.
You use those three ...
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What's the standard deviation of the difference between randomly paired data?
Assume that we want to compare the agreement of two methods of measuring blood pressure (e.g. a machine and a sphygmomanometer). In their paper, Preiss & Fisher (2008) discuss the standard ...
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Just passing through: Estimating the probability that a changing quantity will pass through some value within a time interval?
Suppose I have a quantity that is measured periodically, that is continuous in the following sense: In order for the quantity x to move from x=a to x=b, x must pass through all the values between a ...
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Development of an adaptive scale
I need your help with a problem that I noticed and I don't know the solution (I am not from statistics). In sum, I would like to create a measurement instrument that is adaptive in that respondents ...
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Using items with different numbers of response categories across time points in longitudinal modeling
I'm doing a cross-lagged panel modeling for three time points. For one specific construct of interest, I have three items that were used for across three time points, but the number of items used for ...
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In measurement invariance testing, how can one differentiate between differences in response styles and differences in latent means?
I am trying to establish measurement invariance between two groups on a depression measure: high-school aged boys and high-school aged girls. Though my entire sample reports elevated depression ...
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How to estimate variance when measuring fluctuating variable that never settles?
I am supposed the investigate viscosity related phenomena in water flow through a horizontal pipe, connected to a water tank at one end, and with clear opening on the other. Mounted in the middle is ...
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Error in measurement from two correlated devices
I'll provide physical context just to be able to write my question clearly. In an experiment, we're trying to measure the electric field using a device called an electrofield meter $EFM$. The way it ...
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Detection limit for a drop in speed, due to stopping between measurements
Assume that a device is traveling at a constant expected speed $\mu$, subject to random variation with standard deviation $\sigma$, for a measurement period of duration $t$. Then the expected travel ...
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How to determine sample size for non-normal distributed data with continuous variables?
TLDR: I need to determine the minimum sample size for measuring the energy consumption of code.
Hello, I'm trying to determine how many samples (N) I need in an experiment to be confident that my ...
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How to treat data of one parameter measured with two same devices that show slight differences in averge [closed]
I have measured one parameter with two identical devices. Unfortunately one device shows higher values on average. Also maximum and minimum of the values differ by exactly the same value like the ...
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Measurement of indipendent variables for binary logistic regression
I want to run a binary logistic regression to understanding (modeling) factors affecting nest-site selection in a bird species..I measured 32 presence points and 64 absence points.
Instead of ...
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Do ordering and equal distances imply interval scale?
Variables measured on an ordinal scale have an order but the distance between levels has not to be 'equal'. In case distances would be equal, does this imply the variable is measured on an interval ...
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Are summary statistics of variables interval or ratio?
Would variables that are derived from other variables via summary statistics (e.g., mean, mode, standard deviation) be classified as interval or ratio type? Or neither?
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How should I operationalize my variables?
I am trying to find out whether the regime type of states signing international cooperation agreements influence the design of the agreement, more specifically whether the regime type of the members ...
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Discrimination index or item-test correlation?
The discrimination of an item can be calculated as:
$$D = \frac {K_h-K_l}{N}$$
Where $K_h$ is the number of correct responses from the high scoring group, $K_l$ from the lowest scoring group (top and ...
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what statistic test to use for measuring the differences between the same individual
I am planning to conduct a study to measure the length of the left and right ear on the same individual. I am stumped on which test should i be using and i would be glad if anyone can set me on the ...
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Assay method comparison - Linear mixed effects regression
I am currently studying two methods to measure the same thing (amount of bacteria in a sample). I have measurements of the same samples by method-1 and method-2. These measurements have been taken in ...
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Creating equation for Customer Loyalty Score
Goal is to establish a loyalty score for a customers of particular TV Brand.
Listed below are some factors that I think should logically affect the score.
Features of a Loyalty Score
Loyal Customer ...
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Can I sum random variables and get a semantically useful result?
I repeatedly measure two values, $a$ and $b$. Measurement $a$ correlates with two real values $X$ and $Y$. For measurement $b$ the correlation with value $Y$ should be smaller, maybe even 0 while ...
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Factor analysis between two measures with different age range
is it totally meaningless or impossible to do factor analysis between two measures with different age ranges? For example, I want to test if two personality measures are testing the same underlying ...
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Determine drift
I would like to determine potential drift in the data/device. Is there a general acknowledged procedure and/or method to do so?
I know how to visually "detect" a drift but I would like to ...
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Data simulation in R for Measurement invariance
I am trying to generate random data for an analysis of Measurement invariance. I will be looking at a one-factor model for two groups with 4 variables each.
I would need to generate a sample where I ...
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measurements of (& establishing relationship & confidence between) two related quantities within a margin of error?
There's this shooting game in which the shooting accuracy gets affected by movement, at full movement speed the inaccuracy reaches it's maximum, and at lower speeds (still accelerating), it's a ...
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Are there better measures of entropy
Related question here
I am trying to measure the uniformity of multimodal distributions and am looking into using entropy.
I would like a measure of entropy that is higher for the first distribution ...
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What is the level of measurement of my dependent variable?
For my master thesis I conducted an online experiment where participants had to conduct a shopping task where they were provided with a local and a non-local product three times in a row. So for three ...
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Using Factor Analysis for Items on Different Scales
I have a quick question about factor analysis from different scales. Is it advisable to use, conjunctly, items from different measures? For example, if I am interested in doing EFA in the context of ...
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Categorical or continuous? I can't decide
This may seem like a simple question, but it would be helpful to know others' opinions. I am trying to determine the effect of distance on growth. Growth is a continuous variable (i.e. 2.46cm). ...
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How does measurement invariance work with demographic variables?
I am running an analysis that includes an argument for measurement invariance which can be set as true or false. If true, item-response probabilities are constrained to be equal across groups.
When I ...
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Sample size for medical device which provides repeated measurements
I have a medical device which provides continuous measurements of a substance in the body (X) over time.
There is currently an established reference standard (Y) which measures the same substance but ...
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Describing the measurement of a random variable as another random variable
Background
Suppose we have a box of resistors. The manufacturer rates these resistors at 100 ohms, but they have some variability. Let $x$ be the true resistance of a resistor chosen from the box at ...
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What scale of measurement is percentage?
Is the percentage of marks scored by someone or something like the population growth ratio scale of interval? Like both have an absolute zero so it makes sense for them to be ratio and not interval?
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What are the pre-requisite of a dataset's measurement type before Principal Component Analysis can be used? [duplicate]
Must all the measured data be discrete, continuous, nominal or ordinal? What are some of the transformation techniques that can be used?
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Prior selection in Gaussian - an application to height measurement
Say I have just purchased ACME's Tree Height Measuring Device (THMD). ACME states that the error $\epsilon$ in tree height measurement from this device can be modelled as a normal distribution with ...
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How to express the agreement between experiment and theoretical observation?
Let us suppose I have a value measured from experiment and given by
$$V_{\text{exp}} \pm \sigma_{V_{\text{exp}}}$$ and a theoretical value given as
$$V_{\text{the}} \pm \sigma_{V_{\text{the}}}$$
Is ...
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Understanding Scales of Measurement
Looking through the various Stack Exchange groups, I think this may be the appropriate group. Apologies if I should have posted this elsewhere.
I have been reading about Scales of Measurement (Nominal,...
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Accounting for sampling effort of independent variables in a regression analysis
I would like the test whether the frequency of a cellular structure on a histology section is associated with (binary) patient outcomes. This would be a simple logistic regression of i.e. ...
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When do we REALLY need to distinguish interval from ratio measurement levels?
This question is specifically aimed toward the practice of statistics and data science and toward statistics educators (particularly introductory level statistics).
In brief, ¿when do we really need ...
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Welch-Satterthwaite equation for effective degrees of freedom
Using Welch-Satterthwaite equation to calculate the effective degrees of freedom i got 0.29, is that possible? What is the meaning of that equation and how can i know if I messed up somewhere?
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Measurement error and type I. and type II. error [closed]
Is there a relationship between measurement error (1.) both systematic and random, (2.) systematic only and (3.) random only in terms of tendency of results of statistical tests to be biased towards ...
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Build an index to determine a ranking [duplicate]
Suppose we have a dataframe similar to the following (I have more than 3 columns and all values in the dataframe are in %):
...
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Estimate uncertainty of window average
I have some random process $y(t)$ that represent an unknown signal combined with some random high frequency positive feedback noise, that is noise amplitude grows with the value of the signal.
I think ...
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Metrics to compare diversity of groups on multiple characteristics
When I search for 'diversity metrics' it seems like most work has focused on ecological diversity, and I most frequently see the Simpson diversity index. This is equivalent to the economics metric, ...
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Is body temperature interval or ratio scale?
I understand that temperature is interval scale because it holds no true zero and can represent values below zero. But in case of body temperature it cannot go below a certain point and definitely not ...
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