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What is data analysis?
- to organize and summarize data.
- Individuals vs. variables
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what are the two types of variables?
categorical and quantitive
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what's the 6-W-H
Who, What, Why, Where, When, Whome, How
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what's distribution of varbiables?
list of numbers
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what do yo uuse for categorical variables?
bar graphs and pie charts
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what is used to quantitive variables?
dot plot, stem plots and histograms.
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if the data is too small, what do you use?
a dot plot
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if the data is medium sized what do you use?
stem plot
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if the data is large, what do you sue
histogram
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what is a percentage graph?
an ogive.
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how do you create an ogive graph if you have the class and freguency?
add commulative and percentage columns
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what's one way you can describe distribution?
use SOCS.
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what does SOCS stand for?
Shape, Outlier, Center and Shape
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What types of shapes are there?
- Skewed to the right.
- skewed to the left
- symmetric
- peaks -> Unimodel or Bimodel
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what's an outlier?
something unusual in the pattern
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what's center and spread?
- center is the middle value.
- spread is how the data varies. A.K.A. IQR = Q3-Q1
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what are the 2 ways to describe the center?
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What's the downside of a mean?
aleasily influenced by the outlier. (always follows the outlier.)
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Is the mean a resistant measure?
The mean is NOT a resistant measure.
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How can you find the median?
Arrange from least to greatest and find the middle number
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is the median a resistant measure?
Yes, the median is a resistant measure. It can resists outliers and are less influenced by it.
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If a graph is skewed, do you mean or median?
If the graph is skewed, use median.
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if the graph is normal, do you use mean or median?
If the graph is normal, you use mean.
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How can you report the spread?
by standard deviation and quartiles.
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What are quartiles?
example of Q1 and Q3
- the first quartile : 25th percentile
- the third quartile: 75th percentile.
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what is the five number summary?
Minimum, 1st quartile, center, 2nd quartile, maximum.
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What are box plots used for?
Which questions should you ask yourself when comparing boxplots?
- they are used to compare two or more distributions.
- you should ask yourself:
- -shape
- -outiler?
- -center
- -spread (IQR -> Q3-Q1)
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what is the equation in order to find the outlier?
1.5 x IQR
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What is standard deviation?
it measures how far the majority of the observations are away from their mean. Uses the sigma sign
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