Data Science Flashcards

Question

What is a line chart used for?

Answer 1

A line chart is a graph that uses points connected by lines to show trends over time or ordered categories. It is ideal for visualizing time series data or showing how one variable changes in relation to another, often used to track progression, patterns, or fluctuations.

Answer 2

Data visualization is the process of representing data graphically to make information easier to understand, analyze, and communicate. It helps uncover patterns, trends, and outliers using tools like charts, graphs, and dashboards. Common tools include matplotlib, seaborn, Tableau, and Power BI, Looker Studio.

Answer 3

Pandas is a Python library used for data manipulation and analysis. It provides two core data structures: Series (1D) and DataFrame (2D). Pandas makes it easy to clean, filter, group, merge, reshape, and analyze structured data, especially from CSV, Excel, SQL, and JSON formats.

Answer 4

NumPy (Numerical Python) is a Python library for numerical computing. It provides support for multi-dimensional arrays and matrices, along with a large collection of mathematical functions to operate on these arrays. It's the foundation for scientific computing in Python and is often used with pandas, scikit-learn, and matplotlib.

Answer 5

A DataFrame is a 2-dimensional, tabular data structure in pandas with rows and columns, similar to an Excel spreadsheet or SQL table. Each column can contain a different data type (e.g., integers, strings, floats). It's one of the most commonly used structures for data analysis and manipulation in Python.

Answer 6

.groupby() in pandas is used to split data into groups based on the values in one or more columns. You can then apply aggregations (like .sum(), .mean(), .count()) or custom functions to each group.

Answer 7

A p-value is the probability of obtaining test results at least as extreme as the observed results, assuming the null hypothesis is true. It helps you determine the significance of your results. A small p-value (typically ≤ 0.05) means the result is statistically significant — you may reject the null hypothesis. A large p-value (> 0.05) suggests weak evidence against the null — you fail to reject it.

Answer 8

Combines DataFrames using database-style joins.

Answer 9

A method of making decisions using data, typically involving p-values and significance levels.

Answer 10

df['age'] =

Answer 11

An experiment comparing two versions of something to determine which performs better.

Answer 12

A method of problem solving that tries to identify the primary cause of a problem.

Answer 13

Identifying values that are significantly different from others in the dataset.

Answer 14

Analyzing data points collected or recorded at specific time intervals.

Answer 15

SELECT * FROM customers;

Answer 16

SELECT * FROM table_name WHERE age > 30;

Answer 17

SELECT COUNT(*) FROM table_name;

Answer 18

SELECT * FROM table_name ORDER BY price DESC;

Answer 19

SELECT * FROM orders INNER JOIN customers ON orders.customer_id = customers.customer_id;

Answer 20

import pandas as pd

Answer 21

pd.read_csv('data.csv')

Answer 22

df[df['salary'] > 50000]

Answer 23

for item in items: print(item)

Answer 24

list(range(10))

Answer 25

import numpy as np

Data Science Flashcards

(51 cards)