DSE Cheat Sheet 2026

The 30 highest-yield DSE facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which business intelligence tool is most widely used for creating interactive dashboards without coding? → Tableau
2. Which visualization is most effective for displaying trends of multiple categories over time on the same chart? → Multi-line time-series chart
3. In hypothesis testing, which of the following describes a Type I error? → Rejecting a true null hypothesis.
4. What is the primary analytical purpose of a heatmap in data science? → Visualizing magnitude across a two-dimensional matrix using color intensity
5. Which of the following is an example of a hyperparameter (not a learned parameter) in a neural network? → The learning rate used by the optimizer
6. In a neural network, what is the purpose of the backpropagation algorithm? → Computing gradients of the loss with respect to each weight so they can be updated
7. Why is walk-forward (time series cross-validation) preferred over standard k-fold cross-validation for time series data? → It respects temporal ordering and prevents future data from leaking into the training set
8. Which architectural design is also referred to as a systolic array? → MISD
9. Which of the following best describes the approach used to find previously undiscovered qualities in the data? → Unsupervised Learning
10. Which statistical test is most commonly used to check whether a time series is stationary by testing for a unit root? → Augmented Dickey-Fuller (ADF) test
11. Which activation function is used in the output layer of a binary classification neural network to produce a probability between 0 and 1? → Sigmoid
12. Which loss function is typically used for binary classification problems in neural networks? → Binary cross-entropy
13. In classical time series decomposition, which component represents patterns that repeat at fixed, known intervals such as monthly or yearly cycles? → Seasonal component
14. We put __ in front of the mean to tell Python that we want to use the mean function from the Numpy library. → np.
15. What type of chart is best suited for showing the frequency distribution of a single continuous variable? → Histogram
16. Which of the following is a key characteristic of classification problems in supervised learning? → The target variable is categorical.
17. Which plot is used to determine the order of the autoregressive term (p) when building an ARIMA model? → PACF (Partial Autocorrelation Function) plot
18. What is statistical modeling's shared objective? → Inference
19. What does GAN stand for, and what are its two main components? → Generative Adversarial Network; generator and discriminator
20. In the context of hypothesis testing, what does the statistical power of a test represent? → The probability of correctly rejecting a false null hypothesis.
21. What is the primary goal of data preparation in data science? → To transform raw data into a usable format
22. A _________ representation of data is called a column. → Vertical
23. In the context of building a classification model, what is the primary purpose of a train/test split? → To evaluate the model's performance on unseen data and check for overfitting.
24. What is the primary function of a pooling layer in a Convolutional Neural Network? → Downsampling feature maps to reduce spatial dimensions and computation
25. Which model is most commonly utilized as the standard by data analysis? → Linear Regression
26. In time series analysis, what does 'cointegration' describe? → A long-run equilibrium relationship between two or more individually non-stationary series
27. Select if the following assertion is accurate or not: → False
28. Which type of map visualization is best suited for showing a continuous variable (e.g., population density) distributed across geographic regions? → Choropleth map
29. What property of a time series indicates that its statistical properties such as mean and variance remain constant over time? → Stationarity
30. Which task is completed by a data scientist after the data is collected? → All of the above