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what are the 2 types of data?

What is Categorical data?
Data made up of categories (not numbers) with "usual meaning

How do you compute Relative Frequency?
Frequency divided by total

What is Statistics?
Science of using data to analyze questions of interest and draw conclusions.

What is the experimental unit?
It is the object which you are studying

What is the experimental unit if you're studying the GPA of students?
Each individual student

What is a population in statistics?..give example.
 A collection of all experimental units of interest
 Ex: an entire student body

What is a statistical census?
This is a method for finding attributes of all members of a statistical population of interest

What is a statistical sample?
A subset of an entire population

What are the 3 major branches of statistics?
 Descriptive
 Probability
 Inferential

What is Descriptive Statistics?
Utilizes techniques to describe attributes of data sets

What is Probability Statistics?
This tells us what sorts of inferences we can make about a population based on the sample

What is Inferential Statistics?
Drawing conclusions from a sample that might be applicable to the whole population

What is a statistical variable?
A characteristic of the experimental unit of interest

What are the 2 types of variables?
Categorical and Quantitative

What is a quantitative variable?..and give an example.
 Variable that has natural ordering and are numeric
 Ex: Money

What is a discrete quantitative variable and give an example.
 This is a quantitative variable that can only take discrete numerical values?
 Ex: Integers

What is a continuous quantitative variable..example?
 This is a variable that can take on any numerical value
 Ex: All Real #s

If a variable is bounded, can it not qualify as continuous..exxample?
 No. A variable can be bounded and still be continuous.
 Ex: Nonnegative #s

Found by adding up all of our data and dividing
by number of data points
Mean

If a statistical attribute (ex: mean) changes a lot when we change large values and changes little when we change little values then it is:
Not Resistant

Is mean a resistant statistical attribute?
No

What is median?
The middle value when a set of sample #s are ordered numerically

If a statistical attribute (ex: median) doesn't change at all when a new value is introduced to it then it is...
Resistant


If you have an even number of values, how do you find their median when ordered numerically?
the median is the mean of the middle 2 values in the order.

If the mean is roughly equal to the median, what shape would you expect your data set to be?
Symmetric

What cane you say about the shape of the data if the mean is greater or less than the median?
If mean is greater then positive skewed; if less than the median then it is negatively skewed

What is the mode?
The value that appears most often

This is specifically the equation for...
Sample Standard deviation

This is the formula for...
And what does Mu stand for in this?
 Population Standard Deviation
 Mu is population mean

This is the formula for
Sample Variance (Standard Deviation squared)

What are Q1, Q2, and Q3 for IQR?
 Q1=Median of 1st half of data set
 Q2= median of full set
 Q3= Median of 2nd half of set

Are the quartiles in IQR and the IQR itself resistant?
yes

If you have an odd number of data, what do you do with the middle value when calculating quartiles?
The middle value is included in both Q1 and Q3 calculations.

Name the resistant measures of spread and center

Name the nonresistant measures of spread and center

How do you designate the range in which a value is considered and outlier?
 If it is less than Q11.5*IQR
 or
 If it is greater than Q3+1.5*IQR

When can you drop and observation from a data set?
 When you are certain of it being a mistake
 When you know the observation came from the wrong population

What does the Empirical rule say about data?
68% of data falls within the first standard deviation, 95% falls within the second standard deviation, and 99.7% of the data falls within 3 standard deviations

What are the characteristics of bellshaped data?
 symmetric
 unimodal
 mean and median are relatively close to each other

How do you calculate statistical density?
 Density = Relative Frequency divided by group
 width

What are some topics you should include when summarizing a set of data

What is the easiest way to find the skewness of a set of data?
 Find the mean and compare it to the median
 If the mean is greater than the median then you have positive skew
 If mean is less than median then negative skew

