# Questions tagged [measurement]

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

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17 views

### Measurement invariance across groups and time

I want to run a multi-group longitudinal model. Based on prior invariance testing, I can assume scalar invariance across groups and time. So is it appropriate to have both the same intercepts across ...
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### How to improve testing method B, if Bland-Altman analysis show a near-perfect correlation between the difference and the mean between method A and B?

I have two sets of measurements (two different methods), A and B. Correlation between the measurements is only modest. Therefore, I wondered whether there is some inherent bias in (one or both) of ...
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### Why is reliability a ratio of true score variance to total score variance, instead of the ratio of true score to total score?

Reliability is given by: $r_{xx} = \frac{Var(T)}{Var(X)}$ where $T$ is the true score and $X$ is the total score. Why isn't reliability simply: $r_{xx} = \frac{T}{X}$ where $T$ would be a sum of all ...
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### Dry skull vs live skull measurement adjustments

I am working on a dataset that has dry skull measurements from a museum's collection (twice as many samples) or a live specimen (less common). As you can imagine, the live specimen are on average a ...
82 views

### How to detect a plateau at the end of a short time series?

In exercise testing (spiroergometry), participants' oxygen uptake is measured continuously while they engange in physical exercise that progressively intensifies. The measurements are taken at regular ...
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1 vote
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### CFA Measurement Invariance - can weak invariance be significant with the configural but not strong invariance? [closed]

I am a newbie here. I searched through the forum but did not find similar questions, so I hope someone who is proficient with SEM / lavaan can help out. I am using R lavaan and semTools to perform ...
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### How to compare distributions if some data maxed out instrument/measurement?

I am comparing the distributions for the strength of two part designs. The test equipment maxes out at 300 units. The 300 units is an arbitrary limit of the equipment and does not represent a ...
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### Does measurement invariance analysis assume equal latent scores across groups?

I have completed a measurement invariance analysis comparing high-school aged boys to high-school aged girls on a measure of depression. The results suggest that scores are not (scalar) invariant; ...
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### What is F1 Score for this diagram?

I have this Venn chart that represent a dataset prediction of Identifying if our products are classified as "A41" standard or not The Blue Circle represents a Machine Learning Model ...
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### Is there multi-variate generalized MAPE(Mean Absolute Percentage Error)

The MAPE could be employed in the context of regression problem and is defined by $$MAPE := \frac{1}{n} \sum_{t=1}^{n} \left| \frac{y_{t} - \hat{y}_{t}}{y_{t}} \right|$$ where $y_{t}$ is target ...
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### Response style as an alternative explanation for latent mean differences under scalar invariance?

I established scalar measurement invariance for a two-group CFA. The output from my final model showed that the latent mean in group 1 is lower than the latent mean in group 2. Can this difference in ...
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### What is the (logical) relationship between an measurement instrument's validity and responsiveness?

The three major criteria for the quality of a measurement instrument are validity, reliability, and responsiveness. I understand validity and reliability, but I have trouble understanding the need to ...
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### Is there a standard measurement of 2-dimensional precision?

Suppose a gun is fired at the bullseye of a target a specific number of times. Ignoring the accuracy (e.g. all the shots are well to the left and above the bullseye), is there a standard way of ...
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### "Decade" variable ranging over 130 years - Can I treat this as continuous? I've seen it done with 8pt scales...but it doesn't past the smell test

My dataset includes "decade founded" but not "year founded" for organizations. I need to include some "maturity" variable in the model. Decade is the best I have. The ...
283 views

### How can I calculate a relative measure of change for data series that can include zero?

I have a series of data points representing the number of OKs for a test. For each data point, I want to calculate by how much its value changed compared to the preceding value, and I need this ...
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### Is it valid to take the midpoint of discrete outcome variables that express a range e.g. (1-20%, 21-40%) then calculate the mean of those midpoints?

I work in a health service and have a PhD student who was told by my boss (her primary supervisor) to measure clinicians' responses concerning what proportion of their clients had a certain condition ...
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### Creating Correlation Matrix Tables with multiple variables within one measurement

trying my luck here since no one in my surroundings has worked with SPSS before and I am also clearly a newbie to SPSS and statistics. For my master degree I am researching possible correlations/a ...
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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 ...
1 vote
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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 ...
1 vote
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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 ...
1 vote
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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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### 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 ...
1 vote
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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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### 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 ...
1 vote
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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 [closed]

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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