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18 Cards in this Set
 Front
 Back
what is statistics?

a science of data


what is data?

numbers with a context


what are individuals?

the objects described by a set of data


what is a variable?

any characteristic of an individual


wjat os a categorical variable?

takes numerical values for arithmetic operations such as adding averageraging make sense. The values of quantative variables are usually recorded in a unot of a measurement such seconds or kilograms


what is exploratory data analysis?

uses graphs and numerical summaries to describe the variables in a data set and the relations among them,.


How do we explore data?

begin by exmaining each varibale itself. begin with graphs


what is the distribution of a veriable?

tells us how often it takes these values of a categorical varable are labels of categories


How do you find a mean?

add the values of all the observations and divide by the number of observations


what is a median?

the midpoint of a distribution


how do you find medians?

(1) arrange all observations in order of size, from smallest to largest
(2) if the number of observations is oddd, the median M is the center observation in the ordered list. Find the location of the meidan by counting (n+1)/2 observations up from the bottom of the list. (3) if the number of the observation is even, the median M is the mean of the two center obserations in the ordered list. The location of the median is agains (n+1)/2 from the bottom of the list 

how do you calculate quartarlies?

(1) locate the medium
(2) Q1 is to the left of the median (3) Q3 is to the right 

How do you calculate the IQR?

IQR= Q3Q1


How do you find standard deviation?

(X1MEAN)+(X2MEAN)+(X3MEAN)
OVER N1 TAKE SOLUTION DIVIDE BY N SQUARE ROOT THAT ANWSER 

Approximately 68% of all observation lie between ______ of _________.

the standard deviation
the mean 

approx. 95% of observations fall between _____ of the ______.

2(standard deviation)
of the mean 

approx. 99.7 of observations fall between ________ of the _______.

3(standard deviation) of the mean


If x is an observation from a distribution that has mean and standard deviation, the standardized value of x (often called the zscore) is what?

z= xmean
over standard deviation 