Chapter 1 Flashcards
Types of statistics
Descriptive & Inference
What’s descriptive statistic?
Involves the collection, organization, summarization and presentation of the data.
What’s inference statistic?
Consist of generalizing from samples to population.
What’s Data?
Collections of observations
What’s population and sample?
Population : The complete collection of all the individuals to be studied
Sample : Collection selected from a population
A graduate student conduct a research study on undergraduate student smoking habit. She begins with a survey to 500 randomly selected undergraduate students from 10 randomly selected universities. The 500 students form a sample or population?
Sample
A graduate student conduct a research study on on undergraduate student smoking habit. She begins with a survey to 500 randomly selected undergraduate students from 10 randomly selected universities. The undergraduate students from universities form a sample or population?
Population
What’s a numerical measurement describing some characteristic of a population?
Parameter
” Mean and standard deviation are both parameters”
What’s a numerical measurement describing some characteristic of a sample?
Statistics
” The sample mean and the sample standard deviation are both statistics”
In studying the loggerhead turtle, scientists observe the average mean number of hatchling in all 253 nests. Is the given value a parameter or statistics?
Parameter because “ population “
A sample of batteries lasted an average mean of 9 days. Is the given value a parameter or statistics?
Statistics “sample “
Any quantity that varies. Can have different values
Variables
Two types of variables
Qualitative & Quantitative
Consist of names or labels representing categories
Qualitative
Consist of numbers representing counts or measurements
Quantitive
Types of qualitative
Nominal & Ordinal
Types of quantitative variables
Continuous & Discrete
Result when the number of possible values is either a finite number or a countable number (0, 1, 2, 3, 4, 5) z
Ex: The number of eggs that a hen lays. What kind of data?
Discrete Data
Result from infinitely many possible values that covers a range of values without gaps, interpretations, jumps.
Ex : The amount of milk that a cow produce 2.3728282 gallons per day.
What kind of data?
Continuous Data
The categories have no relation to each other and can’t be arranged in a specific order. Ex: blood groups and gender.
What kind of data?
Nominal Data
Compare between dichotomous and multi-chotomous?
Dichotomous: there are only one of two alternatives of the nominal variables. “Gender”
Multi-chotomous : there are more than two categories. “ blood group”
This kinds of variables have natural order or progression. Ex: low, middle, high. What kind of data?
Ordinal Data
A sample of dall sheep is measured to have an average mean horn length of 35.7 inches. Is the given value a discrete or continuous?
Continuous
The number of hatchlings from a sample of 45 bluebird nests is 135. Is the given value a discrete or continuous?
Discrete
Four levels of measurement
Nominal level , ordinal level, interval level, ratio level.
• Involves data that can be arranged in order
• Differences between data values can’t be measured
Ex: Course grade “ A, B, C, D”
Ordinal level
• Characterized by data that consist of names and labels.
• The data can’t be arranged in order
Ex : survey responses such as yes or no
Nominal level of measurement
• The data arranged in order
• Differences between datas are meaningful
• There’s no natural zero starting point
Ex : years 1000, 2000, 1888.
Interval Level Of Measurement
• There’s a natural starting point
• Differences between data is are meaningful
Ex : prices of books such as 0, 100, 50.
Ratio Level Of Measurement
Doctors measure the weights in pounds of babies. What type of data selected? Ordinal, interval, nominal, ratio.
Ratio
Scientists classify the four major desert using different regions: the great basin, the mohave, the Sonoran. What type of data is selected?
Nominal
The income range of attendees at a research conference is gathered as upper middle and low levels. What type of data is selected?
Ordinal
We obtain data from two sources
Observational and experiment
Methods of sampling
Random
Systematic
Convenience
Stratified
Cluster
Multistage
Equal chance of being selected
Random sampling
Select some starting point and then select every 3 rd kth element
Systematic sampling
Use results that are easy to get
Convenience
Divide the population to groups that share the same characteristics then draw a sample from each form
Stratified sampling
Divide the population are into sections and randomly select some of these groups .Choose all members from selected group.
Cluster sampling
Collect data by using combination of the Basic sampling methods
Multistage sampling
To conduct a study of shareholders attitude. Lists of shareholder zip-codes is compiled. All shareholders from 20 different zip-codes are selected to be surveyed. The type of sampling is
Cluster
To obtain a sample of pregnant women, a researcher contact her son’s preschool. They type of sampling is
Convenience
Biologists divide the regions where red foxes are found into the Australia, oriental, Ethiopian regions. They plan to follow 100 female from each region to find the average. The type of sampling is
Stratified sampling
Types of studies and the differences between them
Cross sectional study : data is collected now
Retrospective study : past
Prospective : future
