Statistics & Probability –
Key Concepts, Data
Analysis & Probability
Study Guide
Updated Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
, Mutually exclusive events Events that can't happen at the same time (no shared outcomes). Ex: getting an A
and a B in the same class
Collectively exhaustive events Events that include every possible outcome in the sample space, so one must
happen. Ex: Pass/Fail
2 branches of statistics Descriptive and inferential
Descriptive statistics Summarizing data with charts, tables, mean, median, etc. Ex: "The average Test 1
score was 82%"
Inferential statistics Using a sample to draw conclusions about a population. Ex: "Schools with free
breakfast see 13.5% fewer fights"
Notation for independent events P(A ∩ B) = P(A) × P(B) (also P(A | B) = P(A))
Z-score How many standard deviations an observation is from the mean. No units. Positive
= above mean, negative = below
Z-score formula z = (x − x̄) / s (population: z = (x − μ) / σ)
Z-score outlier rule z greater than 3 or less than −3
Standard normal distribution (Z) Mean = 0, standard deviation = 1
Population ALL items/members of interest. Ex: all OU students
Sample A subset of the population. Ex: 200 randomly selected OU students
Key Concepts, Data
Analysis & Probability
Study Guide
Updated Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
, Mutually exclusive events Events that can't happen at the same time (no shared outcomes). Ex: getting an A
and a B in the same class
Collectively exhaustive events Events that include every possible outcome in the sample space, so one must
happen. Ex: Pass/Fail
2 branches of statistics Descriptive and inferential
Descriptive statistics Summarizing data with charts, tables, mean, median, etc. Ex: "The average Test 1
score was 82%"
Inferential statistics Using a sample to draw conclusions about a population. Ex: "Schools with free
breakfast see 13.5% fewer fights"
Notation for independent events P(A ∩ B) = P(A) × P(B) (also P(A | B) = P(A))
Z-score How many standard deviations an observation is from the mean. No units. Positive
= above mean, negative = below
Z-score formula z = (x − x̄) / s (population: z = (x − μ) / σ)
Z-score outlier rule z greater than 3 or less than −3
Standard normal distribution (Z) Mean = 0, standard deviation = 1
Population ALL items/members of interest. Ex: all OU students
Sample A subset of the population. Ex: 200 randomly selected OU students
