DS Unit - 2

Unit -II

Descriptive and Inferential statistics, Data visualization, Exploratory data analytics,  Hypothesis testing,Introduction to Artificial intelligence, conventional techniques and Logic  programming, Introduction
to Machine learning, regression, classification (ANN, SVM and  Decision tree) and clustering 

Descriptive and Inferential statistics,

Descriptive statistics and inferential statistics are two main branches of statistics used in data science
to analyze and interpret data.

Descriptive statistics refers to the methods used to summarize and describe the characteristics of
a dataset. This includes measures such as central tendency (e.g. mean, median, mode), dispersion
(e.g. range, variance, standard deviation), and graphical representations (e.g. histograms, box plots,
scatter plots). Descriptive statistics help to understand the overall pattern and distribution of data and
provide insights into the key features of the dataset.

Inferential statistics, on the other hand, involves making predictions or generalizations about a
population based on a sample of data. It uses statistical models and hypothesis testing to infer
conclusions about a larger population from a smaller sample. Inferential statistics are used to test
hypotheses, estimate parameters, and make predictions. It provides insights into the underlying
relationships between variables and helps to draw meaningful conclusions from the data.

In summary, descriptive statistics helps to summarize and describe the characteristics of data,
while inferential statistics helps to draw conclusions about a population based on a sample of data.



Data visualization



Data visualization refers to the graphical representation of data and information to communicate

insights and patterns in a clear and effective manner. In data science, data visualization is an

important tool for understanding and communicating the patterns and trends present in data.


Data visualization can take many forms, including charts, graphs, tables, maps, and infographics.

These visualizations can help to reveal patterns, relationships, and anomalies in the data that might

not be immediately apparent from looking at the raw data alone. They can also help to identify

outliers, detect trends, and communicate insights to stakeholders.


The choice of data visualization depends on the type of data being analyzed and the purpose of the

analysis. For example, a scatter plot might be used to visualize the relationship between two variables,

while a histogram might be used to visualize the distribution of a single variable. A map might be

used to visualize spatial patterns in data, while an interactive dashboard might be used to allow users

to explore and analyze data in real-time.


In summary, data visualization is a critical tool in data science that enables analysts to communicate

insights and patterns in a clear and effective manner. It helps to reveal patterns, relationships, and

anomalies in the data and supports decision-making processes.




Exploratory data analytics,  Hypothesis testing


Exploratory data analysis (EDA) is the process of analyzing and summarizing a dataset in order to

gain insights and identify patterns and relationships in the data. It involves visualizing the data and

calculating descriptive statistics to better understand the structure and characteristics of the data.

EDA is often the first step in a data analysis project, and helps to inform the development of

hypotheses and models.


Hypothesis testing is the process of using statistical tests to evaluate a hypothesis about a population

based on a sample of data. The goal of hypothesis testing is to determine whether the observed results

are statistically significant or simply due to chance. This involves specifying a null hypothesis, which

assumes that there is no significant difference or relationship between variables, and an alternative

hypothesis, which asserts that there is a significant difference or relationship. Statistical tests, such as

t-tests or chi-squared tests, are used to evaluate the evidence against the null hypothesis and determine

the level of statistical significance.


Hypothesis testing is used to support decision-making and to draw conclusions from data.

For example, in a clinical trial, hypothesis testing might be used to determine whether a new

treatment is more effective than a placebo, or in marketing research, hypothesis testing might be used

to determine whether a new advertising campaign has had a significant impact on sales.


In summary, exploratory data analysis is a process of analyzing and summarizing a dataset to gain

insights and identify patterns, while hypothesis testing is a process of using statistical tests to evaluate

a hypothesis about a population based on a sample of data. Both EDA and hypothesis testing are

critical components of data science that support decision-making and enable the development of

models and insights.



 Introduction to Artificial intelligence


Artificial Intelligence (AI) is a field of computer science that focuses on creating intelligent machines

that can perform tasks that normally require human intelligence, such as visual perception, speech

recognition, decision-making, and language translation. In data science, AI is used to analyze and

interpret large volumes of data, identify patterns and trends, and make predictions or

recommendations based on the data.


AI is composed of several subfields, including machine learning, natural language processing (NLP),

computer vision, and robotics. Machine learning is a subfield of AI that involves the use of

algorithms to automatically learn patterns and relationships in data without being explicitly

programmed. Natural language processing (NLP) is a subfield of AI that focuses on the interaction

between computers and human languages, such as speech recognition and language translation.

Computer vision is a subfield of AI that focuses on enabling machines to interpret and understand

visual data, such as images and videos. Robotics is a subfield of AI that focuses on the design and

development of robots that can perform tasks autonomously.


In data science, AI is used to create models that can analyze and interpret large volumes of data to

identify patterns, relationships, and anomalies. These models can be used for a variety of applications,

such as predicting customer behavior, identifying fraud, optimizing supply chains, and diagnosing

diseases. AI models can also be used to automate tasks, such as speech recognition, image recognition,

and language translation.


Overall, AI is a powerful tool in data science that enables analysts to analyze and interpret large

volumes of data and create models that can make predictions and recommendations based on the data.

As AI technology continues to evolve, it has the potential to transform many industries and enable

new applications and capabilities.



conventional techniques and Logic  programming


Conventional techniques refer to traditional approaches used in data science for data analysis and

modeling. These techniques include statistical methods such as regression analysis, hypothesis testing,

and time-series analysis. Conventional techniques also include data pre-processing techniques such

as data cleaning, data transformation, and data normalization.


Logic programming, on the other hand, is a programming paradigm that focuses on the use of logical

statements and rules to express relationships and constraints in data. Logic programming is often used

in data science for knowledge representation and reasoning, such as in expert systems and rule-based

decision making.


One of the most popular logic programming languages used in data science is Prolog, which is

designed for solving problems that involve logical relationships and reasoning. Prolog is often

used in applications such as natural language processing, machine learning, and expert systems.


While conventional techniques are well-established and widely used in data science, logic

programming offers an alternative approach for expressing and reasoning about data relationships

and constraints. Both conventional techniques and logic programming have their own strengths and

weaknesses, and the choice of approach depends on the specific problem and data being analyzed.



Introduction to Machine learning, regression, classification (ANN, SVM and  Decision tree)

and clustering 


Machine learning is a subfield of artificial intelligence that involves the use of algorithms to learn

patterns and relationships in data without being explicitly programmed. Machine learning algorithms

are used to analyze and interpret large volumes of data, identify patterns and trends, and make

predictions or recommendations based on the data. There are several types of machine learning

algorithms, including supervised learning, unsupervised learning, and reinforcement learning.


Supervised learning involves training a model on a labeled dataset, where the desired output or

prediction is known. Two common types of supervised learning algorithms are regression and

classification.


Regression is used to predict a continuous output variable, such as predicting the price of a house

based on its size and location. Linear regression is a popular regression algorithm that fits a linear

equation to the data to make predictions.


Classification is used to predict a categorical output variable, such as whether an email is spam or not.

Popular classification algorithms include artificial neural networks (ANNs), support vector machines

(SVMs), and decision trees.


Artificial neural networks (ANNs) are a type of machine learning algorithm that is inspired by the

structure and function of the human brain. ANNs consist of multiple layers of interconnected nodes

that process and transform data. ANNs can be used for a variety of applications, such as image and

speech recognition, and natural language processing.


Support vector machines (SVMs) are a type of machine learning algorithm that is used for

classification and regression analysis. SVMs work by finding the optimal hyperplane that separates

the data into different classes.


Decision trees are a type of machine learning algorithm that is used for classification and regression

analysis. Decision trees work by recursively partitioning the data based on the values of different

input variables, and can be used to make predictions based on the values of these variables.


Unsupervised learning involves training a model on an unlabeled dataset, where the desired output

or prediction is not known. Clustering is a popular unsupervised learning algorithm that involves

grouping similar data points together. Common clustering algorithms include k-means clustering and

hierarchical clustering.


In summary, machine learning is a subfield of artificial intelligence that involves the use of algorithms

to learn patterns and relationships in data. Regression and classification are two common types of

supervised learning algorithms, while clustering is a popular unsupervised learning algorithm. ANNs,

SVMs, and decision trees are all commonly used machine learning algorithms for classification and

regression analysis.






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