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Jul. 02, 2024
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Companies are striving to make information and services more accessible to people by adopting new-age technologies like artificial intelligence (AI) and machine learning. One can witness the growing adoption of these technologies in industrial sectors like banking, finance, retail, manufacturing, healthcare, and more.
Data scientists, artificial intelligence engineers, machine learning engineers, and data analysts are some of the in-demand organizational roles that are embracing AI. If you aspire to apply for these types of jobs, it is crucial to know the kind of machine learning interview questions that recruiters and hiring managers may ask.
This article takes you through some of the machine learning interview questions and answers, that youre likely to encounter on your way to achieving your dream job.
AI Engineer Master's Program
Explore ProgramLet's start with some commonly asked machine learning interview questions and answers.
There are three types of machine learning:
In supervised machine learning, a model makes predictions or decisions based on past or labeled data. Labeled data refers to sets of data that are given tags or labels, and thus made more meaningful.
In unsupervised learning, we don't have labeled data. A model can identify patterns, anomalies, and relationships in the input data.
Using reinforcement learning, the model can learn based on the rewards it received for its previous action.
Consider an environment where an agent is working. The agent is given a target to achieve. Every time the agent takes some action toward the target, it is given positive feedback. And, if the action taken is going away from the goal, the agent is given negative feedback.
Also Read: Supervised and Unsupervised Learning in Machine Learning
The Overfitting is a situation that occurs when a model learns the training set too well, taking up random fluctuations in the training data as concepts. These impact the models ability to generalize and dont apply to new data.
When a model is given the training data, it shows 100 percent accuracytechnically a slight loss. But, when we use the test data, there may be an error and low efficiency. This condition is known as overfitting.
There are multiple ways of avoiding overfitting, such as:
Also Read: Overfitting and Underfitting in Machine Learning
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Register NowThere is a three-step process followed to create a model:
Consider a case where you have labeled data for 1,000 records. One way to train the model is to expose all 1,000 records during the training process. Then you take a small set of the same data to test the model, which would give good results in this case.
But, this is not an accurate way of testing. So, we set aside a portion of that data called the test set before starting the training process. The remaining data is called the training set that we use for training the model. The training set passes through the model multiple times until the accuracy is high, and errors are minimized.
Now, we pass the test data to check if the model can accurately predict the values and determine if training is effective. If you get errors, you either need to change your model or retrain it with more data.
Regarding the question of how to split the data into a training set and test set, there is no fixed rule, and the ratio can vary based on individual preferences.
One of the easiest ways to handle missing or corrupted data is to drop those rows or columns or replace them entirely with some other value.
There are two useful methods in Pandas:
When the training set is small, a model that has a right bias and low variance seems to work better because they are less likely to overfit.
For example, Naive Bayes works best when the training set is large. Models with low bias and high variance tend to perform better as they work fine with complex relationships.
AI Engineer Master's Program
Explore ProgramA confusion matrix (or error matrix) is a specific table that is used to measure the performance of an algorithm. It is mostly used in supervised learning; in unsupervised learning, its called the matching matrix.
The confusion matrix has two parameters:
It also has identical sets of features in both of these dimensions.
Consider a confusion matrix (binary matrix) shown below:
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%
False positives are those cases that wrongly get classified as True but are False.
False negatives are those cases that wrongly get classified as False but are True.
In the term False Positive, the word Positive refers to the Yes row of the predicted value in the confusion matrix. The complete term indicates that the system has predicted it as a positive, but the actual value is negative.
So, looking at the confusion matrix, we get:
False-positive = 3
True positive = 12
Similarly, in the term False Negative, the word Negative refers to the No row of the predicted value in the confusion matrix. And the complete term indicates that the system has predicted it as negative, but the actual value is positive.
So, looking at the confusion matrix, we get:
False Negative = 1
True Negative = 9
The three stages of building a machine learning model are:
Here, its important to remember that once in a while, the model needs to be checked to make sure its working correctly. It should be modified to make sure that it is up-to-date.
AI Engineer Master's Program
Explore ProgramThe Deep learning is a subset of machine learning that involves systems that think and learn like humans using artificial neural networks. The term deep comes from the fact that you can have several layers of neural networks.
One of the primary differences between machine learning and deep learning is that feature engineering is done manually in machine learning. In the case of deep learning, the model consisting of neural networks will automatically determine which features to use (and which not to use).
This is a commonly asked question asked in both Machine Learning Interviews as well as Deep Learning Interview Questions
Learn more: Difference Between AI,ML and Deep Learning
Machine Learning Deep LearningApplications of supervised machine learning include:
Related Interview Questions and Answers
Supervised learning uses data that is completely labeled, whereas unsupervised learning uses no training data.
In the case of semi-supervised learning, the training data contains a small amount of labeled data and a large amount of unlabeled data.
There are two techniques used in unsupervised learning: clustering and association.
Clustering problems involve data to be divided into subsets. These subsets, also called clusters, contain data that are similar to each other. Different clusters reveal different details about the objects, unlike classification or regression.
In an association problem, we identify patterns of associations between different variables or items.
For example, an e-commerce website can suggest other items for you to buy, based on the prior purchases that you have made, spending habits, items in your wishlist, other customers purchase habits, and so on.
The classifier is called naive because it makes assumptions that may or may not turn out to be correct.
The algorithm assumes that the presence of one feature of a class is not related to the presence of any other feature (absolute independence of features), given the class variable.
For instance, a fruit may be considered to be a cherry if it is red in color and round in shape, regardless of other features. This assumption may or may not be right (as an apple also matches the description).
Reinforcement learning has an environment and an agent. The agent performs some actions to achieve a specific goal. Every time the agent performs a task that is taking it towards the goal, it is rewarded. And, every time it takes a step that goes against that goal or in the reverse direction, it is penalized.
Earlier, chess programs had to determine the best moves after much research on numerous factors. Building a machine designed to play such games would require many rules to be specified.
With reinforced learning, we dont have to deal with this problem as the learning agent learns by playing the game. It will make a move (decision), check if its the right move (feedback), and keep the outcomes in memory for the next step it takes (learning). There is a reward for every correct decision the system takes and punishment for the wrong one.
While there is no fixed rule to choose an algorithm for a classification problem, you can follow these guidelines:
Once a user buys something from Amazon, Amazon stores that purchase data for future reference and finds products that are most likely also to be bought, it is possible because of the Association algorithm, which can identify patterns in a given dataset.
AI Engineer Master's Program
Explore ProgramClassification is used when your target is categorical, while regression is used when your target variable is continuous. Both classification and regression belong to the category of supervised machine learning algorithms.
Examples of classification problems include:
Examples of regression problems include:
Building a spam filter involves the following process:
A random forest is a supervised machine learning algorithm that is generally used for classification problems. It operates by constructing multiple decision trees during the training phase. The random forest chooses the decision of the majority of the trees as the final decision.
There is no master algorithm for all situations. Choosing an algorithm depends on the following questions:
Based on the above questions, the following algorithms can be used:
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AI Engineer Master's Program
Explore ProgramBias in a machine learning model occurs when the predicted values are further from the actual values. Low bias indicates a model where the prediction values are very close to the actual ones.
Underfitting: High bias can cause an algorithm to miss the relevant relations between features and target outputs.
Variance refers to the amount the target model will change when trained with different training data. For a good model, the variance should be minimized.
Overfitting: High variance can cause an algorithm to model the random noise in the training data rather than the intended outputs.
The bias-variance decomposition essentially decomposes the learning error from any algorithm by adding the bias, variance, and a bit of irreducible error due to noise in the underlying dataset.
Necessarily, if you make the model more complex and add more variables, youll lose bias but gain variance. To get the optimally-reduced amount of error, youll have to trade off bias and variance. Neither high bias nor high variance is desired.
High bias and low variance algorithms train models that are consistent, but inaccurate on average.
High variance and low bias algorithms train models that are accurate but inconsistent.
Precision is the ratio of several events you can correctly recall to the total number of events you recall (mix of correct and wrong recalls).
Precision = (True Positive) / (True Positive + False Positive)
A recall is the ratio of the number of events you can recall the number of total events.
Recall = (True Positive) / (True Positive + False Negative)
A decision tree builds classification (or regression) models as a tree structure, with datasets broken up into ever-smaller subsets while developing the decision tree, literally in a tree-like way with branches and nodes. Decision trees can handle both categorical and numerical data.
Pruning is a technique in machine learning that reduces the size of decision trees. It reduces the complexity of the final classifier, and hence improves predictive accuracy by the reduction of overfitting.
Pruning can occur in:
There is a popular pruning algorithm called reduced error pruning, in which:
Logistic regression is a classification algorithm used to predict a binary outcome for a given set of independent variables.
The output of logistic regression is either a 0 or 1 with a threshold value of generally 0.5. Any value above 0.5 is considered as 1, and any point below 0.5 is considered as 0.
K nearest neighbor algorithm is a classification algorithm that works in a way that a new data point is assigned to a neighboring group to which it is most similar.
In K nearest neighbors, K can be an integer greater than 1. So, for every new data point, we want to classify, we compute to which neighboring group it is closest.
Let us classify an object using the following example. Consider there are three clusters:
Let the new data point to be classified is a black ball. We use KNN to classify it. Assume K = 5 (initially).
Next, we find the K (five) nearest data points, as shown.
Observe that all five selected points do not belong to the same cluster. There are three tennis balls and one each of basketball and football.
When multiple classes are involved, we prefer the majority. Here the majority is with the tennis ball, so the new data point is assigned to this cluster.
Anyone who has used Spotify or shopped at Amazon will recognize a recommendation system: Its an information filtering system that predicts what a user might want to hear or see based on choice patterns provided by the user.
Kernel SVM is the abbreviated version of the kernel support vector machine. Kernel methods are a class of algorithms for pattern analysis, and the most common one is the kernel SVM.
You can reduce dimensionality by combining features with feature engineering, removing collinear features, or using algorithmic dimensionality reduction.
Now that you have gone through these machine learning interview questions, you must have got an idea of your strengths and weaknesses in this domain.
Principal Component Analysis or PCA is a multivariate statistical technique that is used for analyzing quantitative data. The objective of PCA is to reduce higher dimensional data to lower dimensions, remove noise, and extract crucial information such as features and attributes from large amounts of data.
The F1 score is a metric that combines both Precision and Recall. It is also the weighted average of precision and recall.
The F1 score can be calculated using the below formula:
F1 = 2 * (P * R) / (P + R)
The F1 score is one when both Precision and Recall scores are one.
Type I Error: Type I error occurs when the null hypothesis is true and we reject it.
Type II Error: Type II error occurs when the null hypothesis is false and we accept it.
Correlation: Correlation tells us how strongly two random variables are related to each other. It takes values between -1 to +1.
Formula to calculate Correlation:
Covariance: Covariance tells us the direction of the linear relationship between two random variables. It can take any value between - and + .
Formula to calculate Covariance:
Support Vectors are data points that are nearest to the hyperplane. It influences the position and orientation of the hyperplane. Removing the support vectors will alter the position of the hyperplane. The support vectors help us build our support vector machine model.
Ensemble learning is a combination of the results obtained from multiple machine learning models to increase the accuracy for improved decision-making.
Example: A Random Forest with 100 trees can provide much better results than using just one decision tree.
Cross-Validation in Machine Learning is a statistical resampling technique that uses different parts of the dataset to train and test a machine learning algorithm on different iterations. The aim of cross-validation is to test the models ability to predict a new set of data that was not used to train the model. Cross-validation avoids the overfitting of data.
K-Fold Cross Validation is the most popular resampling technique that divides the whole dataset into K sets of equal sizes.
Variance: Splitting the nodes of a decision tree using the variance is done when the target variable is continuous.
Information Gain: Splitting the nodes of a decision tree using Information Gain is preferred when the target variable is categorical.
Gini Impurity: Splitting the nodes of a decision tree using Gini Impurity is followed when the target variable is categorical.
The SVM algorithm has a learning rate and expansion rate which takes care of self-learning. The learning rate compensates or penalizes the hyperplanes for making all the incorrect moves while the expansion rate handles finding the maximum separation area between different classes.
There are primarily 5 assumptions for a Linear Regression model:
Lasso(also known as L1) and Ridge(also known as L2) regression are two popular regularization techniques that are used to avoid overfitting of data. These methods are used to penalize the coefficients to find the optimum solution and reduce complexity. The Lasso regression works by penalizing the sum of the absolute values of the coefficients. In Ridge or L2 regression, the penalty function is determined by the sum of the squares of the coefficients.
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With technology ramping up, jobs in the field of data science and AI will continue to be in demand. Candidates who upgrade their skills and become well-versed in these emerging technologies can find many job opportunities with impressive salaries. Looking forward to becoming a Machine Learning Engineer? Enroll in Simplilearn's Caltech Post Graduate Program in AI & ML and get certified today. Based on your experience level, you may be asked to demonstrate your skills in machine learning, additionally, but this depends mostly on the role youre pursuing. These machine learning interview questions and answers will prepare you to clear your interview on the first attempt!
Apart from the above mentioned interview questions, it is also important to have a fair understanding of frequently asked Data Science interview questions.
Considering this trend, Simplilearn offers Caltech Post Graduate Program in AI & ML certification course to help you gain a firm hold of machine learning concepts. This course is well-suited for those at the intermediate level, including:
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Various techniques are used in the search for a mineral deposit, an activity called prospecting. Once a discovery has been made, the property containing a deposit, called the prospect, is explored to determine some of the more important characteristics of the deposit. Among these are its size, shape, orientation in space, and location with respect to the surface, as well as the mineral quality and quality distribution and the quantities of these different qualities.
In searching for valuable minerals, the traditional prospector relied primarily on the direct observation of mineralization in outcrops, sediments, and soil. Although direct observation is still widely practiced, the modern prospector also employs a combination of geologic, geophysical, and geochemical tools to provide indirect indications for reducing the search radius. The object of modern techniques is to find anomaliesi.e., differences between what is observed at a particular location and what would normally be expected. Aerial and satellite imagery provides one means of quickly examining large land areas and of identifying mineralizations that may be indicated by differences in geologic structure or in rock, soil, and vegetation type. In geophysical prospecting gravity, magnetic, electrical, seismic, and radiometric methods are used to distinguish such rock properties as density, magnetic susceptibility, natural remanent magnetization, electrical conductivity, dielectric permittivity, magnetic permeability, seismic wave velocity, and radioactive decay. In geochemical prospecting the search for anomalies is based on the systematic measurement of trace elements or chemically influenced properties. Samples of soils, lake sediments and water, glacial deposits, rocks, vegetation and humus, animal tissues, microorganisms, gases and air, and particulates are collected and tested so that unusual concentrations can be identified.
On the basis of such studies, a number of prospects are identified. The most promising of these becomes the focus of a field exploration program. Several exploration techniques are used, depending on the type of deposit and its proximity to the surface. When the top of a deposit intersects the surface, or outcrops, shallow trenches may be excavated with a bulldozer or backhoe. Trenching provides accurate near-surface data and the possibility of collecting samples of large volume for testing. The technique is obviously limited to the cutting depth of the equipment involved. Sometimes special drifts are driven in order to explore a deposit, but this is a very expensive and time-consuming practice. In general, the purpose of driving such drifts is to provide drilling sites from which a large volume can be explored and a three-dimensional model of the potential ore body developed. Old shafts and drifts often provide a valuable and convenient way of sampling existing reserves and exploring extensions.
The most widely used exploration technique is the drilling of probe holes. In this practice a drill with a diamond-tipped bit cuts a narrow kerf of rock, extracting intact a cylindrical core of rock in the centre (see core sampling). These core holes may be hundreds or even thousands of metres in length; the most common diameter is about 50 mm (2 inches). The cores are placed in special core boxes in the order in which they were removed from the hole. Geologists then carefully describe, or log, the core in order to determine the location and kinds of rock and mineral present; the different structural features such as joints, faults, and bedding planes; and the strength of the rock material. Cores are often split lengthwise, with one half being sent to a laboratory so that the grade, or content, of mineralization can be determined.
DelineationNormally, core holes are drilled in a more or less regular pattern, and the locations of the holes are plotted on plan maps. In order to visualize how the deposit appears at depth, holes are also plotted along a series of vertical planes called sections. The geologist then examines each section and, on the basis of information collected from the maps and core logs as well as his knowledge of the structures present, fills in the regions lying between holes and between planes. This method of constructing an ore body is widely used where the boundaries between ore and waste are sharp and where medium to small deposits are mined by underground techniques, but, in the case of large deposits mined by open-pit methods, it has largely been replaced by the use of block models. These will be discussed in more detail below (see Surface mining).
Mineral deposits have different shapes, depending on how they were deposited. The most common shape is tabular, with the mineral deposit lying as a filling between more or less parallel layers of rock. The orientation of such an ore body can be described by its dip (the angle that it makes with the horizontal) and its strike (the position it takes with respect to the four points of the compass). Rock lying above the ore body is called the hanging wall, and rock located below the ore body is called the footwall.
The concentration of a valuable mineral within an ore is often referred to as its grade. Grade may exhibit considerable variation throughout a deposit. Moreover, there is a certain grade below which it is not profitable to mine a mineral even though it is still present in the ore. This is called the mine cutoff grade. And, if the material has already been mined, there is a certain grade below which it is not profitable to process it; this is the mill cutoff grade. The grade at which the costs associated with mining and mineral processing just equal the revenues is called the break-even grade. Material having a higher grade than this would be considered ore, and anything below that would be waste.
Therefore, in determining which portion of a mineral can be considered an exploitable ore reserve, it is necessary to estimate extraction costs and the price that can be expected for the commodity. Extraction costs depend on the type of mining system selected, the level of mechanization, mine life, and many other factors. This makes selecting the best system for a given deposit a complex process. For example, deposits outcropping at the surface may initially be mined as open pits, but at a certain depth the decision to switch to underground mining may have to be made. Even then, the overall cost per ton of ore delivered to the processing plant would be significantly higher than from the open pit; to pay for these extra costs, the grade of the underground ore would have to be correspondingly higher.
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