Performing a Bayesian Analysis by Hand

Introduction

Bayesian analysis offers the possibility to get more insights from your data compared to the pure frequentist approach. In this post, I will walk you through a real life example of how a Bayesian analysis can be performed. I will demonstrate what may go wrong when choosing a wrong prior and we will see how we can summarize our results. For you to follow this post, I assume you are familiar with the foundations of Bayesian statistics and with Bayes’ theorem.

Scenario

As an example analysis, we will discuss a real life problem from a physics lab. No worries, you don’t need any physics knowledge for that. We want to determine the efficiency of a particle detector. A particle detector is a sensor that may produce a measurable signal when certain particles traverse it. The efficiency of the detector we want to evaluate is the chance that the detector actually measures the traversing particle. In order to measure this, we put the detector that we want to evaluate in between two other sensors in a sandwich-like structure. If we measure a signal in the top and bottom sensors we know that a particle should have also traversed the detector in the middle. A picture of the experimental setup is shown below.

Image for post

We want to measure the efficiency of a particle detector (device under test). Two different sensors (triggers) are placed on top and below the detector in order to detect particles traversing the setup (in this case muons µ).

For the measurement, we count the number of traversing particles N in a certain time (as reported by the top and bottom sensors) as well as the number of signals measured in our detector r. For this example, we assume N=100 and r=98.

#confidence-interval #data-analysis #physics #bayesian-analysis #prior #data analysis

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Performing a Bayesian Analysis by Hand

Performing a Bayesian Analysis by Hand

Introduction

Bayesian analysis offers the possibility to get more insights from your data compared to the pure frequentist approach. In this post, I will walk you through a real life example of how a Bayesian analysis can be performed. I will demonstrate what may go wrong when choosing a wrong prior and we will see how we can summarize our results. For you to follow this post, I assume you are familiar with the foundations of Bayesian statistics and with Bayes’ theorem.

Scenario

As an example analysis, we will discuss a real life problem from a physics lab. No worries, you don’t need any physics knowledge for that. We want to determine the efficiency of a particle detector. A particle detector is a sensor that may produce a measurable signal when certain particles traverse it. The efficiency of the detector we want to evaluate is the chance that the detector actually measures the traversing particle. In order to measure this, we put the detector that we want to evaluate in between two other sensors in a sandwich-like structure. If we measure a signal in the top and bottom sensors we know that a particle should have also traversed the detector in the middle. A picture of the experimental setup is shown below.

Image for post

We want to measure the efficiency of a particle detector (device under test). Two different sensors (triggers) are placed on top and below the detector in order to detect particles traversing the setup (in this case muons µ).

For the measurement, we count the number of traversing particles N in a certain time (as reported by the top and bottom sensors) as well as the number of signals measured in our detector r. For this example, we assume N=100 and r=98.

#confidence-interval #data-analysis #physics #bayesian-analysis #prior #data analysis

Hand Sanitizer in bulk - Get your effective hand sanitizer here

With the spread of various harmful virus globally causing immense distress and fatalities to human mankind, it has become absolutely essential for people to ensure proper and acute hygiene and cleanliness is maintained. To further add to the perennial hardship to save lives of people the recent pandemic of Covid-19 affected globally created the worst nightmare for people of all walks of life. Looking at the present crisis, it has become imperative for human beings to be encouraged to tackle this challenge with an everlasting strength to help protect oneself and their loved ones against the devastating effects of the virus. One thing that stands up between keeping all safe and vulnerable is by making sure that everybody attentively Hand wash periodically to help physically remove germs from the skin and getting rid of the live microbes.

The essence of apposite handwashing is based around time invested in washing and the amount of soap and water used. Technically, washing hands without soap is much less effective anyway. But incase a proper handwashing support system doesn’t become possible around, the usage of Effective Hand Sanitizer will certainly help fight to reduce the number of microbes on the surface of hands efficiently, eliminating most variants of harmful bacteria to settle.

The need has come about for Hand Sanitizer in bulk to save your daily life aptly maintaining a minimum of 60% alcohol - as per the CDC recommendations and approved by USFDA for its greater effectiveness. With the growing demand of people on the move the demand for easy to carry, small, and travel size worthy pouches that are also refillable once the product runs out is the need of the hour. To further make sure that human lives are well protected from these external viruses, it is mandatory for producer of effective Hand Sanitizer to evolve products circumspectly with ingredients that produce not just saving lives but with multiple benefits for people of all ages.

#hand sanitizer #hand sanitizer in bulk #hand sanitizer ingredient #hand sanitizer to alcohol #hand sanitizer travel size #hand sanitizer wholesale

Ian  Robinson

Ian Robinson

1623856080

Streamline Your Data Analysis With Automated Business Analysis

Have you ever visited a restaurant or movie theatre, only to be asked to participate in a survey? What about providing your email address in exchange for coupons? Do you ever wonder why you get ads for something you just searched for online? It all comes down to data collection and analysis. Indeed, everywhere you look today, there’s some form of data to be collected and analyzed. As you navigate running your business, you’ll need to create a data analytics plan for yourself. Data helps you solve problems , find new customers, and re-assess your marketing strategies. Automated business analysis tools provide key insights into your data. Below are a few of the many valuable benefits of using such a system for your organization’s data analysis needs.

Workflow integration and AI capability

Pinpoint unexpected data changes

Understand customer behavior

Enhance marketing and ROI

#big data #latest news #data analysis #streamline your data analysis #automated business analysis #streamline your data analysis with automated business analysis

TensorFlow Performance Analysis

In previous posts (here and here), I told you about how our team uses the Amazon SageMaker and Amazon s3 services to train our deep neural networks on large quantities of data.

In this blog, I would like to discuss how to profile the performance of a DNN training session running in TensorFlow. When speaking of the “performance” of a DNN training session, one may be referring to a number of different things. In the context of this blog, “performance” profiling will refer to analysis of the speed at which the training is performed (as measured, for example, by the training throughput or iterations per second), and the manner in which the session utilizes the system resources to achieve this speed. We will not be referring to the performance of the model being trained, often measured by the loss or metric evaluation on a test set. An additional measure of performance is the number of batches required until the training converges. This is also out of the scope of this blog.

In short, if you are trying to figure out why your training is running slowly, you have come to the right place. If you are searching for ways to improve the accuracy of your mnist model, or are searching for what optimizer settings to use to accelerate convergence, you have not.

The examples we will review were written in TensorFlow and run in the cloud using the Amazon SageMaker service, but the discussion we will have is equally applicable to any other training environment.

Prelude

Any discussion on performance profiling your training requires that we be clear about what the goal is, or, what utility function we are trying to optimize. Your utility function will likely depend on a number of factors, including, the number of training instances at your disposal, the cost of those instances, the number of models you need to train, project scheduling constraints and more.

In order to have a meaningful discussion, we will make some simplifying assumptions. Our goal will be to maximize the throughput of a training session, given a fixed training environment, without harming the quality of the resultant model, or increasing the number of training samples required for convergence.

The goal, as stated, includes some ambiguities that we will promptly explain.

#tensorflow #sagemaker #analysis #performance #data analysis

Tyrique  Littel

Tyrique Littel

1604008800

Static Code Analysis: What It Is? How to Use It?

Static code analysis refers to the technique of approximating the runtime behavior of a program. In other words, it is the process of predicting the output of a program without actually executing it.

Lately, however, the term “Static Code Analysis” is more commonly used to refer to one of the applications of this technique rather than the technique itself — program comprehension — understanding the program and detecting issues in it (anything from syntax errors to type mismatches, performance hogs likely bugs, security loopholes, etc.). This is the usage we’d be referring to throughout this post.

“The refinement of techniques for the prompt discovery of error serves as well as any other as a hallmark of what we mean by science.”

  • J. Robert Oppenheimer

Outline

We cover a lot of ground in this post. The aim is to build an understanding of static code analysis and to equip you with the basic theory, and the right tools so that you can write analyzers on your own.

We start our journey with laying down the essential parts of the pipeline which a compiler follows to understand what a piece of code does. We learn where to tap points in this pipeline to plug in our analyzers and extract meaningful information. In the latter half, we get our feet wet, and write four such static analyzers, completely from scratch, in Python.

Note that although the ideas here are discussed in light of Python, static code analyzers across all programming languages are carved out along similar lines. We chose Python because of the availability of an easy to use ast module, and wide adoption of the language itself.

How does it all work?

Before a computer can finally “understand” and execute a piece of code, it goes through a series of complicated transformations:

static analysis workflow

As you can see in the diagram (go ahead, zoom it!), the static analyzers feed on the output of these stages. To be able to better understand the static analysis techniques, let’s look at each of these steps in some more detail:

Scanning

The first thing that a compiler does when trying to understand a piece of code is to break it down into smaller chunks, also known as tokens. Tokens are akin to what words are in a language.

A token might consist of either a single character, like (, or literals (like integers, strings, e.g., 7Bob, etc.), or reserved keywords of that language (e.g, def in Python). Characters which do not contribute towards the semantics of a program, like trailing whitespace, comments, etc. are often discarded by the scanner.

Python provides the tokenize module in its standard library to let you play around with tokens:

Python

1

import io

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import tokenize

3

4

code = b"color = input('Enter your favourite color: ')"

5

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for token in tokenize.tokenize(io.BytesIO(code).readline):

7

    print(token)

Python

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TokenInfo(type=62 (ENCODING),  string='utf-8')

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TokenInfo(type=1  (NAME),      string='color')

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TokenInfo(type=54 (OP),        string='=')

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TokenInfo(type=1  (NAME),      string='input')

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TokenInfo(type=54 (OP),        string='(')

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TokenInfo(type=3  (STRING),    string="'Enter your favourite color: '")

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TokenInfo(type=54 (OP),        string=')')

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TokenInfo(type=4  (NEWLINE),   string='')

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TokenInfo(type=0  (ENDMARKER), string='')

(Note that for the sake of readability, I’ve omitted a few columns from the result above — metadata like starting index, ending index, a copy of the line on which a token occurs, etc.)

#code quality #code review #static analysis #static code analysis #code analysis #static analysis tools #code review tips #static code analyzer #static code analysis tool #static analyzer