Unit 2- Descriptive Statistics Flashcards
What are common measures of location in central tendency?
Mode, Median, Mean, Percentiles & Quartiles
What is the mode?
most frequently occurring value in a data set
What is bimodal & multimodal?
bimodal- 2 modes listed, multimodal- data set contains more than 2 modes
What is median?
middle value in an ordered array of numbers
What are percentiles?
Percentiles measure the central tendency that divides a group of data into 100 parts
What are measures of variability?
Range, IQR, Mean Absolute Deviation, Variance, Standard Deviation, Z Scores & Coefficient of Variation
What is population/sample variance?
average of the squared deviations from the
arithmetic mean
What is standard deviation?
square root of the variance
What is the Empirical Rule?
Empirical Rule applies when data are approximately normally distributed
What is Chebyskev’s Theorem?
Chebyskev’s Theorem applies to all distributions & can be used whenever the data distribution shape is unknown or non-normal
What is the z score?
Z scores represent the number of s.d. if value (x) is above or below the mean of a set of numbers when the data are normally distributed (z=(x-μ)/σ)
What is the coefficient of variation?
Coefficient of Variation- ratio of the s.d. to the mean, expressed as a % (the higher the %, the riskier it is) C.V.=(σ/μ)(100)=%
What is the coefficient of skewness?
Coefficient of Skewness (Sk=3(μ-Md)/σ) where Md=median (if Sk<0= negatively skewed, sk=0=symmetric or if Sk<0=positively skewed)
What is Kurtosis?
Kurtosis defines how heavily the tails of a distribution differ from the tails of a normal distribution
