Vocab Flashcards
statistics
is the study of how to collect, organize, analyze, and interpret numerical information from data
variables
is a characteristic of the individual to be measured or observed
Individuals
are the people or objects included in the study
quantitative variables
a number we can do math on
qualitative variables
places you in a group
population data
this data is from every individual of interest
ex: every student in class
sample data
this data is from only some of the individuals of interest
ex: just students in front row
parameter statistics
is a numerical measure that describes an aspect of a population
sample statistic
is a numerical measure that described an aspect of a sample
descriptive statistic
involved methods of organizing, picturing, and summarizing info from samples of populations
inferential statistics
involves methods of using information from a sample to draw conclusions regarding the population
what is descriptive statistics
- shape(skewed)(symmetric)
- typical value (mean or median)
- spread (standard deviation or 5 number summary)
- variance (varies how much?)
how do you find out what the shape is?(skewed or symmetric)
is determined by Pearsons coefficient of skewness.
3(mean - median)
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standard deviation
-if answer is less than -1 then its left skewed
-if answer is between -1 & 1 then its symmetric
-if answer is greater than 1 then its right skewed
how do you find out the typical value?
by using the mean or median
-use mean if data is symmetric
-use median if data is skewed
how do you find out the spread?
use standard deviation or the 5 number summary
-if data is symmetric spread will be given by the standard deviation
-if data is skewed spread will be given by the 5 number summary (min, Q1, med, Q3, Max)
how do you find the variability(symmetric)
if data is symmetric, variability will be given by the,
stand. deviation
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mean
-if greater than 0.5 than it varries a lot
-if less than 0.5 than it doesn’t vary much
how do you find the variability(skewed)
if data is skewed, variability will be given by,
Q3 - Q1
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median
-if greater than 0.5 then it varies a lot
-if less than 0.5 then it doesn’t vary much
standard deviation
provides a measure of the overall variation in a data set
-will be small when the data are all concentrated close to the mean, showing little variation or spread
-will be larger when the data values are more spread out from the mean, showing more variation
how do we compare values from different data sets?
0
methods of assigning probabilities
classical, relative frequency, subjective
rules for assigning probabilities
probability must be between 0 & 1
if all events are mutually exclusive (meaning an event can only be in one category total probabilities added up must = 1)
discrete
if a random variable can take on a finite, countable, or listable number of outcomes
continuous
a random variable that has an infinite amount of outcomes
ex: time for a 1 mile run
probability function
the probability function-denoted (p(x)) tells us the probability that the random variable x takes on certain values
sampling errors
non responsive bias
selection bias
halo effect
respondent error
sample methods
simple random
judgement
quota
stratified random
convenience
cluster
systemic
snowball
