Machine learning is one of the most sought-after technologies today, with businesses across industries embracing it to gain a competitive edge. As per recent reports, the global machine learning market size is expected to reach USD 117.19 billion by 2027, growing at a CAGR of 39.2% from 2020 to 2027. With such staggering growth potential, it is no surprise that the demand for skilled professionals in machine learning is skyrocketing.
If you are passionate about exploring data-driven solutions and have a strong grasp of statistical concepts, a career in machine learning could be the perfect fit for you. This interview aims to assess your knowledge of machine learning concepts, algorithms, and tools, and evaluate your problem-solving abilities to help you carve a successful career in this exciting field. If you're preparing for a career in machine learning, our comprehensive guide to Machine Learning Interview Questions will help you ace your interview.
We have divided these interview questions into a few Categories:
Let's get started!
Ans: Machine Learning allows the use of available datasets to understand a specific function that maps input to output in the best possible way. This problem is known as function approximation. Here, approximation is required for the unknown target function that maps all plausible observations based on the given problem in the best way possible. A hypothesis in Machine learning is a model that helps approximate the target function and perform the necessary input-to-output mappings. The choice and configuration of algorithms allows you to define the space of plausible hypotheses that a model represents. In this process, lowercase h (h) is used for a specific hypothesis, while uppercase h (H) is used for the hypothesis space that is being searched. Let us briefly understand these notations:
Hypothesis (h): A hypothesis is a specific model that helps map the input to output; the mapping can be used further for evaluation and prediction.
Hypothesis set (H): The hypothesis set consists of a space of hypotheses that can be used to map inputs to outputs, which can search. The general constraints, here include the choice of problem framing, the model, and the model configuration.
Ans: Keeping up with the latest scientific literature on machine learning is necessary to demonstrate an interest in a machine learning position. This overview of deep learning in nature by the scions of deep learning itself (from Hinton to Bengio to LeCun) is a good reference paper and an overview of what’s happening in deep learning — and the kind of paper you might want to cite.
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Ans: Machine learning is a type of artificial intelligence that focuses on developing computer programs that can access data, learn from it, and make decisions or predictions based on it. It uses algorithms to analyze data, identify patterns and make decisions with minimal human intervention.
Ans: Principal Component Analysis, or PCA, is a multivariate statistical technique used to analyze quantitative data. PCA aims to reduce higher dimensional data to lower dimensions, remove noise, and extract crucial information, such as features and attributes, from large amounts of data.
Ans: Machine learning is all about algorithms that parse data, learn from it, and then apply what they've learned to make sound decisions.
Deep learning is a type of machine learning inspired by the human brain's structure and is particularly useful in feature detection.
Ans: The F1 score is a model's performance indicator. It is a weighted average of a model's precision and recall, with results closer to 1 being the best and those closer to 0 being the worst. It is used in classification tests where true negatives are unimportant.
Ans: A straightaway answer to this is to make our lives easier. Many systems used hardcoded rules containing "if" and "else" decisions to process data or adjust user input in the early days of "intelligent" applications. Consider a spam filter whose job is to move relevant incoming email messages to a spam folder.
Ans: Assume a friend invites you to his party, where you meet strangers. Because you know nothing about them, you will mentally categorize them based on gender, age group, clothing, etc. Strangers represent unlabelled data in this scenario, and classifying unlabelled data points is nothing more than unsupervised learning. Because you used no prior knowledge about people and classified them on the fly, this is an unsupervised learning problem.
Ans: The machine is trained using labeled data in supervised machine learning. The learning model is then fed a new dataset so that the algorithm can provide a positive result by analyzing the labelled data. For example, we must first label the data to train the model before performing classification.
Unsupervised machine learning involves not training the machine with labeled data and allowing the algorithms to make decisions without any corresponding output variables.
Ans: Overfitting is when a model performs too well on the training data but needs to generalize better to unseen data and can happen when a model is too complex for the data available or when parameters are overly adjusted to fit the training data. To avoid overfitting, you should use regularization techniques such as L1 and L2 regularization, dropout layers, and early stopping. You should also split your data into training, validation, and test sets to ensure the model performs well on unseen data. Additionally, it would help if you used cross-validation to help further evaluate the model's performance on unseen data.
Ans: Machine learning algorithms come in an assortment of flavors. Here is a list of them organized by broad category:
Whether they are trained with or without human supervision (supervised, unsupervised, reinforcement learning), The criteria in the diagram below are not mutually exclusive; we can combine them in any way we see fit.
Ans: Support Vector Machines (SVMs) are solid supervised machine learning algorithms for classification and regression tasks. SVMs work on the concept of decision planes to determine decision boundaries. A decision plane separates a set of objects with different class memberships. In SVM, each data item is represented as a point in n-dimensional space (where n is the number of features), with the value of each feature being the value of a particular coordinate.
The next step is to perform classification by finding the hyper-plane that differentiates the two classes properly. The support vectors decide the hyper-plane, simply the coordinates of individual observation. The distance between the hyper-plane and the support vectors is known as the margin.
The goal is to choose a hyper-plane with the maximum possible margin between the hyper-plane and any of the support vectors. Kernel functions transform the data into a higher-dimensional space and then find an optimal hyper-plane in this higher-dimensional space that maximizes the margin between the support vectors. Once the hyper-plane is established, it can easily classify new data by computing the hyper-plane equation.
If the distance from the data point to the hyper-plane is less than a threshold, then the data is classified as one class; otherwise, as the other class. SVMs are used for both linear and non-linear data sets and can be used for classification and regression tasks. SVMs are very effective in high-dimensional spaces with many features and are relatively memory efficient.
We have data (x1, y1), ..., (xn, yn),
and different features (xii, ..., xip),
and y is either 1 or -1.
The equation of the hyperplane H3 is the set of points satisfying:
w. x-b = 0
Where w is the normal vector of the hyperplane. The parameter b||w||determines the offset of the hyperplane from the original along the normal vector w
So, for each I, either x is in the hyperplane of 1 or -1. Basically, xi satisfies:
w. xi - b = 1 or w. xi - b = -1
Ans: Classification is used to produce discrete results and to categorize data. For instance, separating emails into spam and non-spam categories. On the other hand, regression, works with continuous data. A good example of it will be predicting stock prices at a specific point. Classification is a technique for categorizing output into groups. For instance, will it be hot or cold tomorrow? Regression, on the other hand, is used to predict the relationship that data represents. For instance, what will the temperature be tomorrow?
Ans: The Naive Bayes method is a supervised learning algorithm, and it is naive since it makes assumptions by applying Bayes’ theorem that all attributes are independent of each other.
Bayes’ theorem states the following relationship, given class variable y and dependent vector x1 through xn:
P(yi | x1,..., xn) =P(yi)P(x1,..., xn | yi)(P(x1,..., xn)
Using the naive conditional independence assumption that each xiis independent: for all I this relationship is simplified to:
P(xi | yi, x1, ..., xi-1, xi+1, ...., xn) = P(xi | yi)
Since, P(x1,..., xn)
is a constant given the input, we can use the following classification rule:
P(yi | x1, ..., xn) = P(y) ni=1P(xi | yi)P(x1,...,xn)
and we can also use Maximum A Posteriori (MAP) estimation to estimate P(yi)and P(yi | xi)
the former is then the relative frequency of class yin the training set.
P(yi | x1,..., xn) P(yi) ni=1P(xi | yi)
y = arg max P(yi)ni=1P(xi | yi)
The different naive Bayes classifiers mainly differ by the assumptions they make regarding the distribution of P(yi | xi):
can be Bernoulli, binomial, Gaussian, and so on.
Ans: Following are the steps to make a spam filter:
Ans: Pruning is a machine-learning technique. It is used for reducing the size of decision trees. It reduces the final classifier's complexity, which improves predictive accuracy by reducing overfitting.
Pruning can take place in the following ways:
Fashion from the top down. Starting at the root, it will traverse nodes and small subtrees.
Bottom-up style. It will start with the leaf nodes.
Reduced error pruning is a popular pruning algorithm in which:
Each node is replaced with its most popular class, beginning at the leaves.
The change is kept if the prediction accuracy is not affected.
There are benefits to simplicity and speed.
Ans: Reinforcement learning consists of two components - an environment and an agent. The agent performs some actions to achieve a specific goal. Every time the agent performs a task that takes it towards the goal, it is rewarded. And, every time it takes a step that goes against the goal or in the opposite direction, it is penalized.
Earlier, chess programs were used to determine the best moves after a lot research on various factors. Building a machine designed to play such games require specific rules.
With reinforced learning, you do not have to deal with this problem. This is because the learning agent learns while playing the game. It will make a move (decision), check if it’s the correct move (feedback), and keep the outcomes in memory for the next step it takes (learning). There is a reward for every correct decision and punishment for the wrong one.
Ans: A confusion matrix (also known as an error matrix) is a specific table used to analyze the performance of an algorithm. It is mainly used in supervised learning but is also known as the matching matrix in unsupervised learning.
There are two parameters in the confusion matrix:
Actual \Predicted
It also has identical feature sets in both dimensions.
Here,
For actual values:
Total Yes = 12+1 = 13
Total No = 3+9 = 12
Similarly, for predicted values:
Total Yes = 12+3 = 15
Total No = 1+9 = 10
For a model to be accurate, the values across the diagonals should be high. The total sum of all the values in the matrix equals the total observations in the test data set.
For the above matrix, total observations = 12+3+1+9 = 25
Now, accuracy = sum of the values across the diagonal/total dataset
= (12+9) / 25
= 21 / 25
= 84%
Ans: Ensemble learning combines results from multiple machine learning models to improve decision-making accuracy.
For example, a Random Forest with 100 trees can produce far superior results than a single decision tree.
Ans: Assume a friend invites you to his party, where you meet strangers. Because you know nothing about them, you will mentally categorize them based on gender, age group, clothing, etc. Strangers represent unlabelled data in this scenario, and classifying unlabelled data points is nothing more than unsupervised learning.
Because you used no prior knowledge about people and classified them on the fly, this is an unsupervised learning problem.
Ans: Let me show you how to use an analogy:
Imagine that your girlfriend has given you each year a birthday gift for the past ten years. One day your girlfriend comes to you and asks, "Sweetie do you recall all the birthday presents you received from me?
Remember all ten incidents to remain on good terms with your partner. Thus, recall the amount of time you can recall accurately as a percentage of the total amount of events.
If you can remember each of the ten events accurately If you can do, your recall percentage is 1.0 (100 100 percent). If you recall seven events with accuracy, your recall ratio is 0.7 (70 percent)
But you may need to correct some answers.
For example, suppose that you made 15 guesses, of which ten were right and five were incorrect, implying that you could remember all the events but not as precisely.
Thus, accuracy is the proportion of the number of events you can correctly remember to the total number of events you can remember (a mix of incorrect and correct recalls).
In the previous example (10 real-life events, 15 responses, ten correct, five wrong), You will have 100% recall, but the accuracy of your recall is 66.67 percent (10 /15)
Ans: Operating the Receiver, The characteristic curve (or ROC curve) is a fundamental tool for diagnostic test evaluation that plots the actual positive rate (Sensitivity) against the false positive rate (Specificity) for the various diagnostic test cut-off points.
It demonstrates the tension between sensitivity and specificity (any increase in sensitivity will be accompanied by a decrease in specificity).
The more closely the curve follows the ROC space's left-hand and then top borders, the more accurate the test is.
The closer the curve gets to the ROC space's 45-degree diagonal, the less accurate the test is.
The slope of the tangent line gives the likelihood ratio (LR) for that value of the test at a cutpoint. The area under the curve represents test accuracy.
Ans:
Ans: Ensemble learning is a technique for combining multiple Machine Learning models to produce more accurate results. The entire training data set builds a general Machine Learning model. In Ensemble Learning, however, the training data set is divided into multiple subsets, with each subset used to build a separate model. After the models have been trained, they are combined to predict an outcome so that the output variance is reduced.
Ans: To begin, divide the dataset into training and test sets, or use cross-validation techniques to segment the data into composite training and test sets. Then, implement a carefully selected set of performance metrics: here is a fairly comprehensive list. You could employ metrics such as the F1 score, accuracy, and confusion matrix. What matters here is that you show that you understand the nuances of how a model is measured and how to select the appropriate performance measures for the right situations.
Ans: The Kernel trick involves kernel functions that enable higher-dimension spaces without explicitly calculating the coordinates of points within that dimension. Instead, kernel functions compute the inner products between the images of all data pairs in a feature space and allow them the beneficial attribute of calculating the coordinates of higher dimensions while being computationally cheaper than the explicit calculation of said coordinates and can express Many algorithms in terms of inner products. The kernel trick enables us to run algorithms effectively in a high-dimensional space with lower-dimensional data.
Ans: Entropy in Machine Learning is used for calculating the randomness in the data for processing. The more entropy in the given data, the more difficult it becomes to draw any valid conclusion. Let us take the example of a coin toss. This act is random because it does not favor either of the sides - heads or tails. Here, the result for any number of tosses cannot be predicted as there is no definite relationship between the action of flipping and the possible outcomes.
Ans: Machine Learning has various prediction problems based on supervised and unsupervised learning. They are classification, regression, clustering, and association. Classification and regression can be explained in the following ways:
Classification: A Machine Learning model has been created that assists in differentiating data into separate categories. The data is labelled and categorized according to the input parameters.
For example, predictions have to be made on the churning out of customers for a particular product based on some recorded data. There is a 50-50 probability whether a customer will churn out, or not. So, the labels for this will either be “Yes” and “No.”
Regression is creating a model for distinguishing data into continuous absolute values instead of using classes or discrete values. It identifies the distribution movement based on the historical data. It is also used for predicting the occurrence of an event depending on the degree of association of variables.
For example, the prediction of weather conditions depends on various factors. These include temperature, air pressure, solar radiation, elevation, distance from the sea, etc. The relation among these factors aids in predicting a proper weather condition.
Ans: The variance inflation factor (VIF) estimates the volume of multicollinearity in a collection of many regression variables.
VIF = Variance of the model / Variance of the model with a single independent variable
This ratio is calculated for every independent variable. If VIF is high, it shows the independent variables' high collinearity.
Ans: The main difference between a random forest and GBM is how the techniques are used. Random forest predictions use a technique called bagging, and thus is a little advanced. On the other hand, GBM make predictions with the help of a technique called boosting.
Ans: You’ll often get standard algorithms and data structure questions as part of your interview process as a machine learning engineer, which might feel akin to a software engineering interview. In this comes from Google’s interview process. There are multiple ways to check for palindromes—one way of doing so if you’re using a programming language such as Python is to reverse the string and check if it still is equal to the original string, for example. Look out for the category of questions you can expect, akin to software engineering questions that drill down to your knowledge of algorithms and data structures. Make sure you’re comfortable with the language of your choice to express that logic.
Ans: In the real world, the attributes present in data are of different patterns. So, rescaling the characteristics to a standard scale is beneficial for algorithms to process data efficiently.
We can rescale data using Scikit-learn. The code for rescaling the data using MinMaxScaler is as follows:
#Rescaling data
import pandas
import scipy
import numpy
from sklearn.preprocessing import MinMaxScaler
names = ['Abhi', 'Piyush', 'Pranay', 'Sourav', 'Sid', 'Mike', 'pedi', 'Jack', 'Tim']
Dataframe = pandas.read_csv(url, names=names)
Array = dataframe.values
# Splitting the array into input and output
X = array[:,0:8]
Y = array[:,8]
Scaler = MinMaxScaler(feature_range=(0, 1))
rescaledX = scaler.fit_transform(X)
# Summarizing the modified data
numpy.set_printoptions(precision=3)
print(rescaledX[0:5,:])
Apart from the theoretical concepts, some interviewers also focus on implementing Machine Learning topics. The following Interview Questions are related to the implementation of theoretical concepts.
Ans: Consider the following Python code:
bill_data=pd. read_csv( ("datasetsTelecom Data AnalysisBill.csv")
bill_data. shape
#Identify duplicates records in the data
Dupes = bill_data.duplicated()
sum(dupes)
#Removing Duplicates
bill_data_uniq = bill_data.drop_duplicates()
Ans:
Ans: Precision and recall are two ways of keeping a track on the power of machine learning implementation. They are often used simultaneously.
Precision answers, “Out of all the items the classifier predicted to be relevant, how many are actually relevant?”
Whereas recall answers the question, “Out of all the genuinely relevant items, how many are found by the classifier?
In simple language, precision means exact and accurate. So the same will go for our machine learning model if you have a set of items your model needs to predict to be relevant. How many items are truly relevant?
Mathematically, precision and recall can be defined as the following:
precision = # happy correct answers/# total items returned by ranker
recall = # happy correct answers/# total relevant answers
Ans: When calculating loss, we consider only a single data point and then use the term loss function.
When calculating the sum of errors for multiple data, we use the cost function. There is no significant difference.
In other words, the loss function captures the difference between a single record's actual and predicted values, whereas cost functions aggregate the difference for the entire training dataset.
The Most commonly used loss functions are Mean-squared error and Hinge loss.
Mean-Squared Error (MSE): In simple words, we can say how our model predicted values against the actual values.
MSE = √ (predicted value - actual value)2
Hinge loss: It is used to train the machine learning classifier, which is
L(y) = max (0,1- yy)
Where y = -1 or 1, indicating two classes, and y represents the output form of the classifier. The most common cost function represents the total cost as the sum of the fixed costs and the variable costs in the equation y = mx + b
Ans: There are two ways of choosing a coin. One is to pick a fair coin and the other is to pick the one with two heads.
Probability of selecting fair coin = 999/1000 = 0.999
Probability of selecting unfair coin = 1/1000 = 0.001
Selecting 10 heads in a row = Selecting fair coin * Getting 10 heads + Selecting an unfair coin
P (A) = 0.999 * (1/2)^10 = 0.999 * (1/1024) = 0.000976
P (B) = 0.001 * 1 = 0.001
P (A / A + B) = 0.000976 / (0.000976 + 0.001) = 0.4939
P (B / A + B) = 0.001 / 0.001976 = 0.5061
Probability of selecting another head = P(A/A+B) * 0.5 + P(B/A+B) * 1 = 0.4939 * 0.5 + 0.5061 = 0.7531
Ans: Yes, it is possible.
The intercept term refers to model prediction without any independent variable or in other words, mean prediction
R² = 1 – ∑(Y – Y´)²/∑(Y – Ymean)² where Y´ is the predicted value.
In the presence of the intercept term, R² value will evaluate your model with respect to the mean model.
In the absence of the intercept term (Ymean), the model can make no such evaluation,
With large denominator,
Value of ∑(Y – Y´)²/∑(Y
Ans: Converting data into binary values based on threshold values is known as binarizing of data. The values less than the threshold are set to 0, and those more remarkable than the threshold are set to 1. This process is helpful when feature engineering has to be performed and can also be used for adding unique features. Data can be binarized using Scikit-learn.
The code for binarizing data using Binarizer is as follows:
from sklearn.preprocessing import Binarizer
import pandas
import numpy
names = [ Abhi', 'Piyush', 'Pranay', 'Sourav', 'Sid', 'Mike', 'pedi', 'Jack', 'Tim']
dataframe = pandas.read_csv(ur1, names=names)
array = dataframe. values
# Splitting the array into input and output
X = array[:,0:8]
Y = array[:,8]
binarizer : = Binarizer(threshold=0.0).fit(X)
binaryx = binarizer.transform(X)
# Summarizing the modified data
numpy.set_printoptions (precision=3)
print(binaryX[0:5,:])
Ans: The first condition states that if the sum of the values on the 2 dices is equal to 7, then you win $21. But for all the other cases you must pay $5.
First, let’s calculate the number of possible cases. Since we have two 6-sided dices, the total number of cases => 6*6 = 36.
Out of 36 cases, we must calculate the number of cases that produces a sum of 7 (in such a way that the sum of the values on the 2 dices is equal to 7)
Possible combinations that produce a sum of 7 is, (1,6), (2,5), (3,4), (4,3), (5,2) and (6,1). All these 6 combinations generate a sum of 7.
This means that out of 36 chances, only 6 will produce a sum of 7. On taking the ratio, we get: 6/36 = 1/6
So this suggests that we have a chance of winning $21, once in 6 games.
So to answer the question if a person plays 6 times, he will win one game of $21, whereas for the other 5 games he will have to pay $5 each, which is $25 for all five games. Therefore, he will face a loss because he wins $21 but ends up paying $25.
Ans: Iris dataset is used for implementing the KNN classification algorithm.
# KNN classification algorithm
from sklearn. datasets import load_iris
from sklearn.neighbors import KNeighborsClassifier
import numpy as nр
from sklearn.model_selection import train_test_split
iris_dataset=load_iris()
A_train, A_test, B_train, B_test = ztrain_test_split(iris_dataset["data"], iris_datase
kn = KNeighborsClassifier(n_neighbors=1)
kn.fit(A_train, B_train)
A_new = np.array([[8, 2.5, 1, 1.2]])
prediction = kn.predict(A_new)
print("Predicted target value: {}\n".format(prediction))
print("Predicted feature name: {}\n".format
(iris_dataset[ "target_names"][prediction]))
print("Test score: {: .2f} .format(kn.score(A_test, B_test)))
Output:
Predicted Target Name: [0]
Predicted Feature Name: [' Setosa']
Test Score: 0.92
Ans: Gini index and Node Entropy assist the binary classification tree in decision-making. Basically, the tree algorithm determines the feasible feature that is used to distribute data into the most genuine child nodes.
According to the Gini index, if we a randomly pick a pair of objects from a group, then they should be of identical class and the probability for this event should be 1.
The following are the steps to compute the Gini index:
Compute Gini for sub-nodes with the formula: The sum of the square of probability for success and failure (p^2 + q^2)
Compute Gini for split by weighted Gini rate of every node of the split
Now, Entropy is the degree of indecency that is given by the following:
Where a and b are the probabilities of success and failure of the node
When Entropy = 0, the node is homogenous
When Entropy is high, both groups are present at 50–50 percent in the node.
Finally, to determine the suitability of the node as a root node, the entropy should be very low.
Ans: Handling High Variance
Bagging algorithm is the best pick for handling issues of high variance.
The bagging algorithm would split data into subgroups with a replicated sampling of random data.
Once the algorithm splits the data, we can use random data to create rules using a particular training algorithm. After that, we can use polling for combining the predictions of the model.
In practice, XML is much more verbose than CSVs and takes up much more space. CSVs use some separators to categorize and organize data in proper columns. XML uses tags to outline a tree-like structure for key-value pairs. You’ll often get XML back to semi-structured data from APIs or HTTP responses. In practice, you’ll want to ingest XML data and try to process it into a usable CSV. This question tests your familiarity with data wrangling, sometimes messy data formats.
Ans: A/B Testing is a Statistical hypothesis testing for a randomized experiment with two variables, A and B. It is used to compare two models that use different predictor variables to check which variable fits best for a given sample of data.
Consider a scenario with two models (using different predictor variables) that can be used to recommend products for an e-commerce platform.
Can use A/B Testing to compare these two models to check which one best recommends products to a customer.
Ans:
Ans: The four basics of machine learning are:
Ans: Some common machine-learning interview questions include:
Ans: The seven steps of machine learning are:
Ans: The three types of machine learning are:
Conclusion:
Machine learning is an exciting field with a lot of potential for growth and innovation. Whether you're just starting out or you're a pro with loads of experience, you can totally up your game and impress potential employers with some key preparation. With these interview question and tips you are able to verse yourself with the basics and extremens of machine learning. And of course, be prepared for those tricky Machine learning interview questions.
Moreover, don't let the interview process discourage you. The job outlook for machine learning professionals is looking good, with a projected job growth of 21% from 2018-2028 according to the Bureau of Labor Statistics. So if you're interested in pursuing a career in machine learning, go for it! You've got this.
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