# Questions tagged [units]

units of measurement. Use this tag also for dimensional analysis.

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### log relative luminance unit conversion

i have data provided with relative luminance in specific units (ft*L), different from mine (cd/m^2). these units can be converted linearly between each other, but the problem is the data is provided ...
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### Planning exploratory factor analysis at the organisation level: is my data appropriate?

I am attempting to model (let us say) education system responses to student safety incidents, how schools learn from these incidents and what improves this process. My statistics is basic undergrad ...
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### How do the units of the SIR model cancel out?

I was having trouble trying to understand the parameters of the simplest SIR model. If beta is the effective contact rate and s is the percentage of people who are susceptible, then how do the units ...
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### Units of measurement and the t-statistic

Consider a case in which we want to examine the effect of house value on homeupkeep expenditure using linear regression model, where dependent variable y is the upkeepexpense and ...
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### How to interprete a scaled response variable as an unscaled response variable?

I'm new to R and I'm having trouble to interpret the estimates of my scaled response variable. I used (scale) function to standardize all my variables (1 response ...
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### Standardizing versus percentile rank with survey data

I am currently working with survey data, collected across different locations, but with slightly different units of measurement. For example, on questions such as "What is your level of education", ...
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### Sampling Methods/Monte Carlo method and Log-normal distribution

I found a problem from some notes i found online, here is a screenshot: I am trying to understand this question, it seems this function they define as the LIP() function is basically the quartile/...
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### Can a ratio level variable have negative values?

According to Stevens (1946) ratio level variables require an absolute zero. The implication, I believe, is that 0 = an absence of the thing being measured. As such, can ratio level scales have ...
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### What do “scales” refer to when comparing correlation matrix to covariance matrix?

In one post it was written that: You tend to use the covariance matrix when the variable scales are similar and the correlation matrix when variables are on different scales. What does scale ...
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### Dimensional analysis for a qdf/quantile function correspondng to the pdf/CDF (income distribution example)

This question is a duplicate of a question I previously asked, here: Dimensional analysis for a qdf/quantile function corresponing to the pdf/CDF (size distribution of income example). I believe I ...
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### Can I use a dataset even if the observations of a variable are not in the same unit?

I am using a dataset where a variable is "height". However, when I read about the construction of the dataset, it seems that some observations in the dataset are labelled in centimetres and others in ...
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### What are the units of entropy of a normal distribution?

I have a random process that follows a normal distribution. It's parameters are mean = 35 units, std.dev. = 8 units. I've seen from the wiki entry for the normal distribution that there is a formula ...
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### Change of units in linear regression [duplicate]

Take the following sample linear regression equation: $$\hat{y} = 20 + 50X$$ I understand how a change of units in X that consists of simple scalar multiplication would alter the regression ...
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### The unit of Root Mean Square Error (RMSE)

What is the unit of root mean square error (RMSE)? For example if we get an RMSE of 47 from a regression model, what does it tell in terms of unit?
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### If I divide my data by its mean, does it still have a unit?

When dividing a timeseries by its mean value so that its mean becomes 1, does the resulting data still have a unit or is it unitless?
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### What are the tests to measure agreement between two methods of measurement when the unit of measurement is different between the two methods?

Bland-Altman plot measure the agreement between two different methods which measures the same variable. As far as I understand Bland-Altman can measure only if the two methods have the same unit of ...
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### Changing the units for an independent variable in a Poisson model

I'm trying to model a dose-response relationship between the incidence of cancer (dependent variable, counts) and the radiation dose (independent variable in gray). Can I change the unit of the ...
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### lognormal distribution, standard-deviation and (physical) units

I have a distribution of microparticles that follows a lognormal distribution. The cumulative distribution function thus is given by:  F_X(x;\mu,\sigma) = \frac12 \operatorname{erfc}\!\left(-\frac{\...
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### Z-score calculation for a single variable with readings in multiple units

I ran into little trouble transforming a set of data I need for analysis. I have been trying to analyze results of a lab test as Z-scores. I have an output field with a reading and unit field. Data ...
301 views

### Getting the units right for the Pareto distribution of wealth: x = people, dollars, dollars per person?

When people talk about the 80-20 rule in the context of wealth, it is usually expressed, verbally, by stating that the 20 percent of the people with the highest wealth get 80 percent of the wealth, ...
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### What is a dimensionless indicator?

What is a dimensionless indicator? I assume it refers to the fact that it is consistent in the way that it doesn't vary disproportionately at the variation of its factors.
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### Consideration of type/unit errors relevant in statistics and correlation studies?

In http://www.academia.edu/1067827/Defence_of_Empirical_Evidence, Paul Cockshott argues that "type error" must be considered. So, the type of the average cost of the unit of oil is dollars/barrel, ...
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### Re-expression units conversion

I was arguing with my Stats teacher today in class because we were stuck on the topic of re-expression. She decided to give me extra credit if I could prove to her, using the internet, something ...
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### The organization as a unit of analysis and sampling issue

I'm doing a quantitative study entitled "Technology Transfer and Competitive Advantages in Oil and Gas Companies". In my study, the unit of analysis is the organization and there are only 9 oil and ...
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### What rules should guide scaling variables to maximise interpretation, particularly within a regression context?

Context: In this previous question @adhesh asked about the benefits of coding a binary variable zero-one rather than one-two. I realised when I wrote this answer that I had quite a lot to say about ...
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### Why is gender typically coded 0/1 rather than 1/2, for example?

I understand the logic of coding for data analysis. My question below is on the use of a specific code. Is there a reason why gender is often coded as 0 for female and 1 for male? Why is this coding ...