Statistical Concepts and Analysis Flashcards
7 cards from real Data Science practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Statistical Concepts and Analysis flashcards as text
Which statement about correlation and causation is correct?
Answer: Correlation does not imply causation
Two variables can move together due to confounders or chance without one causing the other.
The power of a statistical test is the probability of:
Answer: Correctly rejecting a false null hypothesis
Power equals 1 minus the Type II error rate—the chance of detecting a real effect.
Which test is most appropriate for comparing the means of two independent groups?
Answer: Independent samples t-test
An independent samples t-test compares means between two separate groups.
A z-score of 2.0 tells you that a value is:
Answer: Two standard deviations above the mean
A z-score expresses how many standard deviations a value lies from the mean.
Which scenario describes selection bias?
Answer: A survey sample systematically excludes part of the target population
Selection bias arises when the sample is not representative because certain groups are systematically over- or under-included.
When a dataset is heavily skewed, which transformation is commonly used to reduce skewness?
Answer: Log transformation
A log transformation compresses large values and often makes right-skewed data more symmetric.
What is the purpose of a chi-square test of independence?
Answer: To assess whether two categorical variables are associated
The chi-square test of independence checks for association between two categorical variables.