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Questions tagged [arithmetic]

For on-topic questions involving arithmetic. Try to include also a more statistical tag. For purely mathematical questions about arithmetic, please use math SE https://math.stackexchange.com/

92 questions
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Converting (normalizing) very small likelihood values to probability

I am writing an algorithm where, given a model, I compute likelihoods for a list of datasets and then need to normalize (to probability) each one of the likelihood. So something like [0.00043, 0.00004, 0.00321] might be converted to may be like…
Ikram Ullah
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20
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Log probability vs product of probabilities

According to this wikipedia article, one can represent the product of probabilities x⋅y as -log(x) - log(y) making the computation more computationally optimal. But if I try an example say: p1 = 0.5 p2 = 0.5 p1 * p2 = 0.25 -log(p1) - log(p2) = 2 p3…
spacemonkey
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6
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2 answers

Exception for sum of deviations from mean being 0

I was reading here the sum of the deviations about the mean will be 0, except for possible rounding. Could anyone explain me the what does it mean? I know about sum of deviations from mean being zero but what about this except for possible…
Naga
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What does it mean to use a normalizing factor to "sum to unity"?

Would you also be able to provide an example? I have very little mathematical/statistical knowledge and have never understood normalization.
Anonymous
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4 answers

Converting a Model from square feet to square meter

I have a simple regression fit for predicting house prices from square feet. The estimated intercept is -44850 and the estimated slope is 280.76 To make predictions for inputs in square meters, what intercept and slope must we use ?
mdsds
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4
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Reasons not to use fuzzy numbers instead of pds to represent uncertainty

Can someone explain why (if at all) it would be a bad idea to use fuzzy numbers in order to represent uncertainties in model parameters instead of probability distributions? To motivate my question - assume a decision model where the parameters are…
David
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4
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1 answer

How to calculate 'times likely' for a percentage and whole number data set?

I'm analyzing speech data for single people vs those in group. I have two types of datasets for which I want to calculate "times likely". Data 1 (probability). Low Music Single 0.6 Group 0.8 #This refers to probability…
Biotechgeek
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4
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2 answers

Difference between geometric and arithmetic mean

I still have problems to exactly understand the difference between geometric and arithmetic mean. I know that e.g. for returns, the arithmetic mean can be wrong (e.g. if I start with 100 $ and if my stock then goes up +10%, and then from 110 it goes…
jeffrey
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4
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1 answer

What are the units of the second derivative?

Generally, what are the units of the second derivative? In this (very specific) example I have plotted height against gap probability, what should I put in place of the "?".
kungphil
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3
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Weird formula for linear regression

I'll try to make the matter as clear as possible given the circumstances. My boss asked me to look at an old report a former employee wrote around a couple of months ago. Apparently the report contains some very useful information but,…
Edgar Derby
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3
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1 answer

Performing calculation of a product of a sequence,

I have performed a calculation that a sample of records will contain at least 1 defective record assuming replacement. There are 20,000,000 records in the population, 7,000 are defective, and I will be taking 200,000 samples. Assuming…
Brandon
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3
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Which statistic to prove that one data point dominates the proportions in dataset?

I have a skewed distribution where one datapoint (google, see below) dominates the dataset (the Visits metric). I can intuitively see that the %CR for the entire data set (calculated as Total Transactions/Total Visits) is driven by this data point.…
needlesslosses
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How can I normalize price history between -1 and 1 while keeping the ratio of price differences to each other the same?

I want to normalize a series of numbers to all be between -1 and 1, but I would like to do it in a way where the relative difference between price elements stays the same, if possible. Example list of price series price_list = np.array([4.8, 7.2,…
Renoldus
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3
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Modelling exchange rates: how to log transform percentage changes?

I'm trying to model an exchange rate to test for extreme values. However, I have percentage changes from day to day. Given some changes are negative, I can't take the logarithm. Any idea how I could go about log transforming my data set? I know I…
Jackson12
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