MAT 121 Lecture Notes - Lecture 2: Simple Random Sample, Systematic Sampling, Level Of Measurement
5 May 2018
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First Lecture:
Statistics- the science of learning from data
● Statistics includes collecting data, organizing data, analyzing data, drawing conclusions
from data and presenting study results.
● We often want to know a specific piece of information about a large group of people or
things. If we could get this information from every person or thing in the group, then we
would not need statistics.
The two main activities of statistics:
● Estimating a characteristics of the population
○ Examples: What percentage of American adults live more than 150 miles away
from their parents.
● Testing a hypothesis or claim about the population
○ In the third quarter of 2016, 10.9% of US adults were without health insurance,
representing a new low.
Example1: Suppose a company wants to estimate on avg how long a call is received by
customer service lasts. Ten calls were randomly selected.
Call
1
2
3
Length
77
289
128
● This table is a set of data
● Each call here is a case
● The numbers “1” through “10” are called labels.
● The characteristic, length is a variable
● The numbers, 77, 289, 128, is called a distribution.
New Words:
● In a study we collect information (data) from cases. Cases can be individuals,
companies, animals, plants or any objects of interest.
● A variable is any characteristics of a case. A variable varies among cases.
● A label is a special variable used in some data sets to distinguish the different cases.
Each case has a unique label. Also, a label is not a variable we are interested in at all.
Only used to tell cases apart.
● The distribution of a variable tells us what values the variable takes and how often it
takes values.
● Data consists of numbers or categories recorded for the cases along with the context.
Methods of Sampling
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Statistics includes collecting data, organizing data, analyzing data, drawing conclusions from data and presenting study results. We often want to know a specific piece of information about a large group of people or things. If we could get this information from every person or thing in the group, then we would not need statistics. Examples: what percentage of american adults live more than 150 miles away from their parents. Testing a hypothesis or claim about the population. In the third quarter of 2016, 10. 9% of us adults were without health insurance, representing a new low. Example1: suppose a company wants to estimate on avg how long a call is received by customer service lasts. This table is a set of data. The numbers 1 through 10 are called labels. The numbers, 77, 289, 128, is called a distribution. In a study we collect information (data) from cases. Cases can be individuals, companies, animals, plants or any objects of interest.
