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FSU - STA 2122 - Class Notes - Week 1

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Preliminary Definitions

Data is information. When we collect data, we are collecting information.

Subjects: The objects from whom, or about whom, data is collected. The objects may be living or nonliving, tangible or intangible, may consist of events or abstract concepts. One way to Identify the subjects in a story is to first identify the sample size "n", then ask yourself "n of whom/what are we getting information about". We also discuss several other topics like What is a functional groups?

We also discuss several other topics like What is the area of accounting that serves the decisionmaking needs of internal users?

Observation / Response / Data Point: A single collected data value (a piece of information). One way to identify the observations is to first identify the subjects, then ask yourself "from each subject what piece of information are we getting". Another way to identify the observations is to identify the variable in question, that is, identify the missing word in this story involves the distribution of __" Sometimes the words used to describe the subjects and the observations are the same. ("Variable" and "distribution" are explained on later pages.)

Population: The entire group of subjects that we wish to get information about in a single study. In reality, It is often time-consuming or costly to obtain data from the entire population under consideration, so we usually work with samples. We also discuss several other topics like What is is AJ Oparin's importance?

Don't forget about the age old question of What is is used to format the structure and style of a Web page?

Sample: A subgroup of subjects within a population. In real life, we would obtain data from a sample instead of a population, and then use our knowledge of statistics to make inferences about the population from which the sample was drawn.

Sample size: The number of subjects involved in a study, i.e., the number of subjects in the sample. We also discuss several other topics like is4100

Parameter: A numerical measurement that describes a characteristic of a population. We also discuss several other topics like What is the concept of progress?

Statistic: A numerical measurement that describes a characteristic of a sample. Very often sample statistics are used as estimates for the corresponding population parameters.

The table below Shows the symbols used to represent some Parameters and statistics.

Symbol

Name

Population Parameter

(generally Greek letter)

Sample Statistic

(generally Latin letters)

Size

N

n

“N” often denotes total sample size when more than one sample is involved

Mean (average)

(mu,”myoo”)

Variance

(sigma-squared)

s2

Standard deviation

(sigma)

s

Proportion / Percent

(pi, “pie”)

p

Correlation

(rho, “rho”)

r

The picture below may help you to understand the concept of population, sample, parameter and statistics better.

Rectangle represents POPULATION

Some parameters of the population are:

Mean, std devn, proportion/percent,,correlation()

1. We want to know what percent of this term's Statistics students are taking French. We randomly select 40 students in our Statistics class and ask if they are taking French, answer YES or NO. It turns out that 15 of them say YES so we calculate that 15/40=37.5% of them are also taking French. FSU administrators want a truer percent so they poll all of this term's Statistics students and find that 29.8% of them are also taking French. Identify the following in the story.

Subjects: sterns statistics students Observations: the yes/no answer

Sample size: 40 Parameter: 298%

Statistic: 37.5%

2. You want to know the mean age (average age) of all the persons living in your household so you do the calculation and the mean turns out to be 16.4 years. Your teacher wants to estimate the mean age of all the persons living in your household so she asks you your age, and you happen to be 20 years old, so she says that her estimate is 20 years. Identify the following in the story.

Subjects: all the persons living in your house Observations:age or each person

Sample size: 1 Parameter: 16.4 year mean age

Statistic: 20 year meon ago