Introduction and basic definitions Flashcards
What is Statistics?
A science involving the extraction of information from numerical data obtained during an experiment or from a sample
What does method of practice does Statistics Involve?
- The DESIGN of the experiment or sampling procedure,
- collection of the data,
- ANALYSIS of data,
- and making INFERENCES (statements) about larger groups based on data collected.
What is Population?
The entire group of individuals(subjects) about which the researcher wants info.
What are 2 examples of Population?
- All US citizens
2. All female students at the university
What is Parameter?
Some Characteristics of the population that the researcher wants to measure.
What are some examples of Parameter?
- Proportion(part) of us citizens who voted in the last presidential election
- Average (mean) height of all male students at this university
- Proportion (Part) of all sections of all courses taught by part time faculty
What does Proportion mean?
A part of the whole
What does Average mean?
A number expressing the central value in a set of data
In relation to Parameters, the Average or Mean of a population is indicated by what?
the Greek letter μ (mu). Looks like backward u or y
In relation to Parameters, the Proportion (part) of a population that are “successes” is often indicated by what?
The greek letter π (PI)
What is Sample?
A subset of the population that we examine in order to gather information
What is an example of a Sample?
if population of university were all male students, then male students in a certain class would be a sample.
What is a Statistic?
A descriptive measure, usually computed from a sample, which can be expressed or evaluated numerically.
What is an example of Statistic?
if population was all male students, and male students in a class is the sample, then the AVERAGE HEIGHT of the male students would be a Statistic.
In relation to Statistic, What is the Average or mean indicated by?
x̄ (X bar)
In relation to Statistic the Proportion (part) of a sample that are successes are indicated by what?
p̂ (P-hat)
What is an Inference?
A statement about a population based on the data collected in a sample.
Example of an Inference
Using a sample statistic (like the average height in a class (x̄ )) to ESTIMATE a population parameter (an inferred answer for the whole group (μ ))
What is Distribution?
A Listing of all possible values that a characteristic can take and the number (or percentage) of times.
What is a major component of Statistics?
Describing the Distribution of a set of data.
What is one example of Distribution?
- consider gender of a student. students are either male or female.and if you count the number of each that’s the distribution.
What are the two Branches of statistics you deal with usually?
Descriptive, and Inferential Statistics.
What is Descriptive Statistics?
NUMERICAL AND GRAPHICAL techniques for describing characteristics of a population and comparing characteristics among populations
What is Inferential Statistics?
where you use data and statistics computed from a sample to make inferences (statements) about a population.
Often the inference in Inferential Statistics is based on some Descriptive Statistic that has already been computed or created?. T/F?
True. because based on the numerical or graphical data computed within descriptive statistics (usually from a sample of the pop) you are able to transfer that to inferential statistics to use that data to estimate a charecteristic about the population parameter (Average height)
What is a goal of Statistics?
To measure some characteristics about a subject or a set of subjects.
When using statistics what are two methods to assure accurate results?
REPLICATION AND REPETITION
- replicating trials and measure the characteristic on several subjects. (sample)
- if only one subject, repeat measurements several times
What is repetition/replication?
repeating measurement for more accurate result. it is in repeated experiments that statistics become important
it is in repeated experiments that statistics become important? T/F?
True
What is a Constant?
Measurement of some characteristic does not change in repeated trials over time.
Example of a Constant?
- Number of days in January each year? Always 31
2. Number of minutes in an hour? Always 60
What is a Variable?
When measurements of characteristics vary/change from trial to trial.
Examples of a Variable?
- Height of student
2. Grades on tests
In statistics we are not primarily concerned with the observation of variables? T/F
F. We are primarily concerned with the observation of variables. Reason being, of we know what they measurment is going to be there is no reason for repeated experiments but that is seldom
What two Categories are variables classified in?
Qualitative and Quantitative.
What is a Qualitative Variable?
May vary in name or size, but not in degree (level)/ no order or ranking applied
What are three examples of a Qualitative Variable?
- Gender- male or female
2 Eye color- any kind
SSN- A number that is used to identify a person
What is a Quantitative Variable?
measurements vary in size from trial to trial. some order or ranking can be applied.
Examples of Quantitative Variable?
- # of students in a particular class
- weight of a typical student
- grades on tests
What are the two subsets of Quantitative Variables?
Discrete, and Continuous.
What is a Discrete Quantitative Variable?
Measurements can assume only a COUNTABLE # of possible values.
What are some examples of a Discrete Quantitative Variable?
- # of students in a particular class
- Number of cars in parking deck
- Grades on a test
What is a Continuous Quantitative Variable?
measurement can assume any one of a countlessnumber of values in a line interval. usually something measured or calculated like rates averages proportions percentage.
What are some examples of a Continuous Quantitative Variable?
- Weight of a typical students
2. percentage of students who pass the course.
In most problems the data that we have is what?
a sample of the population
What is the goal for using the sample data?
Apply it and make statements about the population as a whole
What letters will be used to indicate Parameters and what letters will be used to indicate Statistics?
- Greek letters indicate parameters
2. English letters indicate Statistics
The type of analysis to be performed is dependent on what?
The type of data collected. Hence being able to identify whether a variable is qualitative or quantitative. o assure the appropriate analysis is done.
