CH 1 Flashcards
Sample Mean Equation
x̄ = ( Σ xi ) ÷ n
(Average)
Sample Standard Deviation Equation
s = √[ (∑(xi − x̄)^2) / (n - 1) ]
Define Sample Variance
s^2 = (∑(xi − x̄)^2) / (n - 1)
Define Outlier Points
Points that are much larger or smaller than the rest.
Sample Median
The sample median is the middle number when the values are ordered from smallest to largest.
Note: When odd find the mean of the two middle numbers.
Define Mode
The sample mode is the most frequently occurring value in a sample.
Define Range
The range is the difference between the largest and smallest values in the sample.
Define Quartiles
Quartiles divide the sample into fourths.
Define Percentile
Percentile is the percentage of values in a sample that fall below a given value. It describes how a value compares to other values from the same sample.
Define Statistics
- Summarizing /describing /visualizing data.
- Using collected data to draw inference about unknown outcomes.
- Exploring the mathematical foundation which support the inference we draw.
Define Parameter
A numerical summary of a population.
Define Population
The collection of all subjects of interests
Define Sample
A sample is a subset of a population containing the objects or outcomes that are actually observed.
Define Subject
A person, place or thing from which we collect.
Define Variable
A characteristic of a subject which varies in a non-random way.
Random Variable
A variable whose outcome is the result of some random process.
Define Simple Random Sample
A simple random sample of a size n is a sample chosen by a method in which each collection of n population items is equally likely to compromise the sample, just as in a lottery.
Define the four types of variables.
- Categorical(Qualitative): Variables which are naturally measured as labels.
+Nominal: Labels with no natural rank/order
+Ordinal: Labels with natural rank/order - Numerical Random Variable(Quantitative): Variables that are naturally recorded/collet as numbers.
+Continuous Random Variable: Number which can theoretically take on any values in a certain interval.
+Discrete Random Variable: Discrete random variables can only take on a finite number of values
Define Randw
The maximum difference in values of data set.
Define Interquartile Range (IQR)
Difference between Q_1 and Q_3
Define Sample Variance
Typical squared deviation from the mean.
Define Sample Standard Deviation
Categorical data
For summarizing categorical data have /frequency relative frequency. (Sample population)
+frequency: number of sample items that fall in same category
+relative frequency = frequency/samplesize. Always between 0 and 1. Percentage number.
