Questions tagged [chemistry]

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Difference between the terms "Frequency" and "Abundance"

How does Abundance or Relative abundance (Chemistry) differs from statistical frequency? Or it is just another term for statistical frequency in context of chemistry? Update: here are some example ...
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What is the distribution of the pKa from the Henderson-Hasselbalch equation given log-normal concentrations?

Background The Henderson-Hasselbalch equation is given by $$\text{pH} = \text{pK}_{\text{a}} + \log_{10} \left( \frac{[\text{Base}]}{[\text{Acid}]} \right)$$ where $\text{pH} = -\log [\text{H}^+]$. ...
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Question about confidence interval and standard errors on graphs

So I made a graph in R, it’s a linear regression of the same sample at different concentrations. It has a confidence interval built into it of 95%. Then I had to determine the concentration of an ...
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How can I use the trend of a graph to plot the next point?

I created a hypothesis for a chemistry assignment and then conducted an experiment. The experiment resulted in a graph that had a downward trajectory. It looked like this: I found the data points by ...
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Graph Classification via Random Forest

This is my first post here, just a brief presentation: my name is Gianmarco, I’m Medicinal Chemistry undergraduate student who is preparing his dissertation, my idea would be to create a classifier ...
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computing model averaging of coefficients of select models using cencorreg function from NADA2 package

I am using the cencorreg function in the NADA2 package to examine the relationship between chemical concentrations in various types of tissues (4 tissues = protein, polar-lipids, non-polar lipids, and ...
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How to test if a river affect another?

I have two rivers, two monitoring stations placed in each river, and two datasets. One river is a tributary of the other. The datasets are complete, pH, metals, field parameters (flow, temperature, ...
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Model Architectures for functional graph or data series type data regression problems using PyTorch, FastAi or TensorFlow

For a university assignment, I am currently trying to build an optical sensor to supervise chemical reactions in pipes. Two sensors are installed in the pipe, around 1mm apart from each other, and ...
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Determining whether new data is "in distribution" with training data

I'm hoping to use machine learning to predict chemical properties of various molecules. Many chemistry machine learning research papers that I come across talk about model generalizability issues ...
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How do I record randomly assigned data succinctly in a table

Please forgive me if I am posting this in the wrong forum. Here is the context of my question: I am conducting a drug trial, of sorts. I have 7-8 potential candidates for the treatment. Between ...
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Clustering data based on correlation

I have a dataset where each row represents a sample and each sample is described by its chemical composition. You can see the 10 first rows of the dataset in figure 1. Figure 1 - Each row represent a ...
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Function to fit acid reaction curve

Data in the image below shows a variable DME reacting to the increase in acid concentration. It looks like it has a very fast increase from when the concentration is raised from 0 to 0.5 and then a ...
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Which statistical test should I use, t-test or another one?

I want to compare two samples. Each of them was dried by two different methods, and I studied their physicochemical characteristics (pH, titratable acidity, total sugars, etc.) to see the influence of ...
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How to estimate the uncertainty of a function that has to be solved numerically

Consider I have a function: $PV_m^3 - PbV_m^2 +aV_m+ab=RT$ In this example I have measured the uncertainties in $P$ and $T$ experimentally and the errors in $a$ and $b$ can be assumed to be zero. ...
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can the parameters of this nonlinear equation be reliably estimated using a limited set of experimental data?

A chemical system at equilibrium is described by this equation: $$ D_{tot} = D + D \cdot \frac {P \cdot X}{D+K_P} + D \cdot \frac {E}{D+K_E} $$ The only parameters that the experimenter can control (...
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Adjacency matrix of amino-acid residue [closed]

How to get the mathematical representation of the chemical bonds in protein residue or the whole protein? Is it possible to get the connectivity matrix or a pairwise description? The example in the ...
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Can one use parametric regression tests (e.g., Pearson's R2) on summary statistics (that are normal) derived from non-normal data?

Can one use parametric linear regression tests (e.g., Pearson's R2) on summary statistics (e.g., mean and median) that are normal but derived from non-normal data? I am specifically dealing with mean ...
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Intersections of chemistry and statistics

I am asking this question for a friend who knows a lot of chemistry and is now studying statistics, primarily since he heard this is the age of data and one should know statistics. However, he is ...
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Dimensions of clustering results

My PhD research (computational organic chemistry) often generates large data sets (>10000 entires) of 'conformers' - where a conformer is basically the spatial arrangement of atoms in space. From ...
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What test is appropriate for my data?

I have three types of food (Fish, Beef, Pasta) and for each food I have the average of the pH level. For each food and pH level, I have three repeated measures showing the amount of aluminum. I want ...
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Analyzing a chemistry experiment - Sampling without replacement

I've been reviewing the results of an interesting chemistry experiment a colleague of mine was conducting, and she sought some help analyzing the results. Would you be able to help, please? The ...
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Correlation between chemical analysis results

I have performed chemical analysis on a sample and the resulting data is something like this: "Carbon: 1.2%, Iron: 50%, Vanadium 2.3% ..." and so on. I have 25 sets of similar data taken from other ...
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What kind of neural network for varying size input & multiple values to predict

I am fairly new to neural networks, I have experience implementing a few simple CNN and RNNs. I really appreciate any advice. I am looking to train a NN to predict the binding affinity for protein ...
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Find (latent) variables which correlate with age of samples (Time series correlations)

I have 8 samples of whisky which are all from the same producer, matured in the same type of casks. However, the casks were (naturally) different. My ages range from 5 years to 32 years old, but ...
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Elementary Statistics book using Chemistry Data Sets

I searched a lot but could not find an Elementary Statistics book using Chemistry data sets for examples and exercises. I would highly appreciate if someone point out me such books.
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Is it possible to use PCA twice, first on several subsets of data, and then again on the main components of those subsets?

I am interested in understanding if it is possible to use PCA twice, first on several subsets of data, and then again on the main components of those data subsets. I'm not entirely sure if this will ...
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1 answer
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Choice of statistical test - confirmation

I want to know if I'm choosing the right statistical test for my situation. Description: In a production process there are several places where wastewater is created (lets call these "spots", spot 1,...
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29 votes
1 answer
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When if ever is a median statistic a sufficient statistic?

I came across a casual remark on The Chemical Statistician that a sample median could often be a choice for a sufficient statistic but, besides the obvious case of one or two observations where it ...
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2 votes
1 answer
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Compare two samples?

Similar questions have been asked but have not managed to get a conclusion from them. I am comparing two sets of samples, where ratios have been obtained for several analytes per sample. So the values ...
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6 votes
1 answer
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How to predict a binary outcome with unbalanced repeated measures data?

I’m somewhat lost as to how to approach a problem I have and was hoping someone can suggest the most appropriate method. The problem: I have a data set consisting of concentration values for 8 ...
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Evaluating a clinical test

I need to evaluate a test (posterior predictive value) but the test results can change based on certain other independent factors. Let's say my test measures a biochemical value but depending on what ...
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