Descriptive statistics Flashcards
What describes central tenancy?
Mean, median, mode
What are quantiles?
The cut off points dividing sections of data
What are quartiles
When there are 4 quantiles
What are percentiles?
When there are 100 quantiles
What is variance?
the measurement of the spread between numbers in a data set
What is standard deviation?
the standard distance from the mean
What is Z-score?
A ratio that describes distance from the mean when given SD
How is Z-score calculated?
(actual value - mean)/ SD
What is skewness?
measures the degree of asymmetry
What is kurtosis?
measures the sharpness
Directions of positive and negative skew
postive = to the right
negative = to the left
What can cause outliers?
- Inaccuracies in data processing
- Problems with methodology
- An actual extreme value due to an unusual participant.
What is inter quartile range?
the width between the 1st and 3rd quartile.
How can the inter quartile range detect outliers?
It is an outlier is the value is greater than 1.5 IQR above the 3rd quartile, or smaller than 1.5 IQR below the 1st quartile
What is binomial distribution?
the discrete probabilistic distribution of the number of events occurring
What is cumulative probability?
the probability that a value falls into a certain range. E.g. if you toss a coin 100 times, what is the probability of tossing heads less than 40 times?
How is binomial distribution computed?
By pascal’s triangle or binomial tables
What is two-tailed probability?
The cumulative probability from both ends of a set of data
What is discrete distribution?
a probability distribution where the random variable can only take on a finite or countable number of values e.g binomial distribution
What is continuous probability distribution?
probability when a continuous random variable X can take on any value within a given range of values ‒ which can be infinite, and therefore uncountable
