# Tagged Questions

Measurement is the assignment of a number to an observation.

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### What is the difference among Indicator, Index, Variable and Measure?

What is exactly the difference among Indicator, Index, Variable and Measure? I would appreciate some reference.
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### Imprecise measurements and observation model

I am using sequential filtering framework to estimate the average speeds on different freeway segments from spot speeds obtained from multiple vehicles. Consider a mile-long stretch of a freeway, and ...
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### What is the substantive meaning of scalar invariance?

I understand that scalar invariance, in the context of Structural Equations Modeling (SEM), is having the intercepts for observed variables loading on the same latent variable be invariant across ...
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### Can some variables be ordinal or interval/ratio, depending on the context?

I believe that some variables can be interval/ratio or ordinal based on the context. I'd like to know people's opinion on this. Let me explain: Class variable with categories Freshman, Sophomore, ...
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### Inter-rater agreement with multiple raters

Compare inter-rater reliability between 8 human experts and a computer I am running a study where I use automated analysis to analyse an EEG signal (brain activity) and quantify certain properties ...
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### Is regression of x on y clearly better than y on x in this case?

An instrument used to measure the levels of glucose in a person's blood is monitored on a random sample of 10 people. The levels are also measured using a very accurate laboratory procedure. The ...
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### Financial instruments ranking based on price movement (outliers, consistency)

I have a lot of financial instruments and I need to rank them based on price movement "stability", i.e. instruments with with big outliers should have the lowest ranks and instruments with stable and ...
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### Non-overlapping state and measurement covariances in Kalman Filter

I have implemented an EKF to track the state of a moving vehicle in 3D. My question is twofold: What happens if a measurement (e.g., for $y$ velocity) has a covariance that does not overlap with the ...
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### Measure for the uniformity of a distribution

I can't seem to find a well established and simple statistical measure of uniformity in occurrence datasets in the presence of zero-valued categories. I've looked at Shannon's entropy which seems to ...
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### SEM: Do I still have to look at the fit of measurement models when overall fit is good?

I have a question concerning structural equation modeling: If the overall fit of my model is very good like in the following model, do I still have to test whether the fit of each measurement model is ...
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### Creating a meaningful statistic measure for physical geography

I'm writing a paper on the collapse of ancient agricultural terraces in the Mediterranean, and have come across a problem when trying to create a meaningful measure. I have sampled with a GPS ...
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### Found a better measurement - what to do with the old/new measurement (both formative)?

In a survey, I used a measurement of uncertainty as a key dependent variable, and after implementing the measurement in 2 waves of my survey, I found a better measurement and this new measurement has ...
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### F-measure for document clustering evaluation - NaN

I'm developing the Java application for text document clustering, and I'm researching some evaluation methods. I implemented F-measure (http://en.wikipedia.org/wiki/F1_score), but I have a problem - ...
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### Determining the “dominant” color in an image

I'm attempting to make a simple mosaic generator, where it takes a photo, then uses hundreds of other photos to represent each pixel. To do so, I want to determine the dominant color of each picture I ...
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### Comparing Multiple Measures of the Same Quantity

I have a program that samples a large number of 'possibilities' (i.e. choices of components for some vector $[a_1, a_2, \ldots, a_N]$), that can each be fed into a collection of different functions ...
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### How many measurements should be done?

I am measuring time of a computer operation. The operation should run roughly same time each time I measure it. How many times should I measure it to get good average and standard deviation? ...
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### Covariance of function uncertainty, why (J^T)*S*J? [duplicate]

As I understand it; to get the uncertainty of a function that is based on some measurements, the derivative of this function with respect to this measurment has to be calculated, and multiplied by ...
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### Measuring Diversity - Blau's Index + Adding Weighting

I would like to use Blau's Diversity Index for the following Data: Functional Diversity in Partners (based on 4 functions = 4 categories) Industry Diversity in Partners (based on SIC codes & 5 ...
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### how to report that we use linking item response score in dissertation?

I refer many thesis both PhD and Masters,but none reported on this matter where the situation that they use one questionnaire to measure a variable, however the questionnaire have two version that ...
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### Can all methods made for certain level in measurement hierarchy used at all higher levels?

Let's say there's a measurement hierarchy for discrete variables, that looks like nominal (grade pass/fail) < ordinal (grade A/B/C) < interval (grade 90-100; 80-89; 70-79, etc). Hierarchy is ...
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### interval or ratio?

I have a question about how to interpret some discrete data. Some are very easy, like the number of children in a household: that is a discrete and numerical, measured as a ratio variable. Other ...
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### Predict missing value(s) using existing measurement's data

I have a few measurements (6) with 13 different features (so I have more parameters than measurements). Let's say I would have a new measurement with a few missing values, considering I have existing ...
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### What do you call a measurement that's halfway between ordinal and interval?

Suppose you have a measurement $Y_i$. Now suppose that the differences between two measurements $\delta_{ij}=Y_i-Y_j$ are an ordinal measurement. From my understanding, $Y_i$ is more informative ...
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### Statistical Model - question on the product measure for a non-parametrical model

A non-parametric statistical model can be defined as follows: $$\{\Xi,\mathcal{B},\mathcal{P}\}$$ where $\Xi$ is the sample space, $\mathcal{B}$ is a $\sigma$-algebra and $\mathcal{P}$ is a ...
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### Assessing the ability of two quantitative methods measuring the same thing

Suppose I have two scientific approaches to measuring the same physical quantity taking values between $[0,1]$. One (say method A) is generally accepted to be more accurate under certain conditions, ...
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### How to evaluate a curve considering outliers?

I have data on runners who run marathons; for each runner I have their final times on a number of races. I would like to predict how fast they are running considering outliers i.e. he's running ...
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### Level of uncertainty when measuring a period of time?

I need to create a raw data table for my science experiment, but I'm unsure what the level of uncertainty would be when measuring days. How would I determine the level of uncertainty when measuring a ...
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### Can statistics based on crude units of measure be improved?

I'm collecting online recipes in order to calculate average ingredient proportions for, say crepes or pastry. Most volume based units of measure in english recipes (cups, tablespoons, teaspoons) ...
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### What helps (justification) to decide cut score/cutoff points for 5-point likert scale?

I am wondering what are the factors involved in deciding the cutoff value / cut score for 5-point likert scale from: ...
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### Conversion between units of measurement

I have two different measuring instruments, A and B, both measure the same physical quantity but with different unit of measures: $u_A$ and $u_B$. A is a reference instrument. I measured a reference ...
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### Can unsupervised evaluation measures for clustering replace a supervised evaluation measure?

Is it possible to have the same evaluation performances when comparing some clustering algorithms using many unsupervised evaluation measures instead of a supervised one ?
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### When is appropriate to run a factor analysis at items level vs. scale level in a new questionnaire?

I am doing a research validating a new questionnaire, which has 156 items divided up in 12 scales. I have run a factor analysis at scale level, which gives me two nice constructs (consistent with ...
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### Interpreting t-value as a measure of evidence

Came across an article on the web on "evaluation of training effectiveness". The author suggests that the "t-value" obtained from a "Paired t-test" conducted using pre-test and post test scores can ...
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### What level of measurement is a factor score?

After doing a factor analysis, I decide to use that factor to test a hypothesis. However, I am not sure what data type of the Factor score the is (i.e., nominal , scale, etc.). Can I do a t-test or ...
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### Exploratory factor analysis among items with different measurements

I intend to do an exploratory factor analysis among items that have different types of measurements: for example, some items have bounded scales (1-100%), some items take small and other large values ...
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### Inferring a likely full population from multinomial measurement or survey data

Assume that we have one or several multinomial samples (e.g., surveys) taken from our population. While inferring characteristics (such as mean values, correlation, ...) from a multinomial sample is a ...
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### How to test if reading from two devices are significantly different?

I am trying to compare readings from an old flowmeter and a new digital flowmeter to find out if they are significantly different. With the new meter I did readings under different conditions eg. ...
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### Evaluation measure of clustering (without having truth labels)

I'm clustering a set of data but I don't have truth document that allow me to evaluate the result of clustering (I have unlabelled data), so I can not use an external evaluation measure. In this case, ...
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### Probability of a measurement under a continuous model

I may be measuring the length of a stick. I then want to see what is the probability of one measurement under a model. When using a continuous model, the probability of a single number is zero:  ...
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### Likert scale categories and composite scores

I have used the following Likert scale for a series of questions in a survey: 0 = Not Important 1 = Slightly Important 2 = Moderately Important 3 = Very Important 4 = Extremely Important As I ...
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I will be conducting an experiment during which I need to measure mental load. After some research I decided on subjective measurements, as I can't obtain the equipment needed to attempt objective ...
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### How to correctly describe measurement variation (over multiple repetitions)

Firstly, please forgive my lack of statistics knowledge, but I am hoping someone can clear up my misunderstandings. I am taking a sample of a physical quantity, (for example: temperature). To take ...
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### How do economists quantify black market operations?

I was doing a lot of research into organized crime in East Asia for a project as a favor to an author-friend of mine, and I noticed that there were noted economists and journalists who, in ...