QU1 Chapter 1 Flashcards
Why does a manager need to know about statistics
- to know how to properly present information
- to know how to draw conclusions about populations based on sample information
- to know how to improve processes
- to know how to obtain reliable forecasts
What is the growth of development of modern stats?
- needs of government to collect data on its citizenry
- which lead to the development of the mathematics of probability theory
- the evolution of electronic computing
definition of population:
(universe) is a collection of things under consideration
Definition of sample
portion of the population elected for analysis
definition of parameter
summary measure computer to describe a characteristic of the population
definition of statistic
summary measure computed to describe a characteristic of the sample
definition: descriptive statistics
collection, presentation and characterization of data
Definition: Inferential Statistics
estimation of a characteristic of a population or drawing conclusions concerning a population based only on sample results.
What is descriptive Statistics - eData collection, presentation and characterization
data collection - survey
data presentation - tables and graphs
data characterization - eg. sample mean
describe mean average and
need more
Describe inferential statistics
estimation - eg. estimate the population mean weight using the sample mean weight
Hypothesis testing - eg. test the claim that the population mean weight is 120 pounds
(draw conclusions and /or making decisions concerning a population based on sample results)
Why is data needed?
- to provide input to survey
- to provide input to study
- to measure performance of service or production process
- to evaluate conformance to standards
- to assist in formulating alternative courses of action
- to satisfy curiosity
What are the two data sources
- primary data collection
2. Secondary data compilation
What does primary data collection consist of
- observation
- Survey
- experimentation
what does secondary data compilation consist of
print or electronic
what is a random variable
definition of possible outcomes of interest form an experiment
what are the types of random variables
- categorical (qualitative)
2. Numerical (quantitative)
What are the two types of numerical (quantitative)
- Discrete (counting)
2. Continuous (Measuring)
what are the reasons why we want to draw a sample
- less time consuming than a census
- less costly than a census
- less cumbersome and more practical to administer than a census of the targeted population
What are the types of sampling methods
- Non-probability samples
2. Probability samples
what are the probability samples
- simple random
- systematic
- stratified
- cluster
what are the Non-probability samples
- Judgement
- quota
- Chunk
What is a simple random (watch a video) need more detail (replacement or replacement???)
- every individual or item form the frame has an equal chance of being selected
- selection may be with replacement or without replacement
- samples obtained from a table of random number for computer random number generators
What is systematic
- Decided on sample size : n
- divided frame of N individuals into groups of k individuals: k= N/n
- randomly select one individual from the 1st group
- select every k-th individual thereafter
What is a stratified sample
- population divided into two or more groups according to some common characteristic
- simple random sample selected form each group
the two or more samples are combined into one
What is cluster
- population divided into several “Clusters” each representative of the population
- simple random sample selected from each
- the samples are combined into one
what are the advantages and disadvantages of simple random sample
- simple to use
- may not be a good representation of the population’s underlying characteristics
what are the advantages and disadvantages of stratified sample
ensures representation of individuals across the entire population
what are the advantages and disadvantages of cluster sample
- more cost effective
- less efficient (need larger sample to acquire the same level of precision)
what are some questions to ask when evaluating survey wrothiness
- what is the purpose of the survey
- is the survey based on probability sample?
- coverage error - appropriate frame?
- non-response error - followed up?
- measurement error - good questions elicit good responses
- sampling error - always exists. reduced by taking large samples
what are the types of survey errors
- coverage error
- non response error
- sampling error
- measurement error
what is coverage error
certain groups are excluded from the frame, therefore they have no chance of being included
what is non response error
- must follow up with non responses
what is sampling error
chance differences form sample to sample
what is measurement error
bad question, leading questions must be avoided
Halo effect
and respondent error - overzealous or under zealous efforts by the respondend
what is data
data is a set of numbers that represent some type of metric or measurement
what is information
information is what the data means
Descriptive statistics according to cga
how data is organized, described and presented
- statistics such as mean (average), variance, range etc.
- organized and presented using tables, charts etc.
Inferential statistics according to CGA
drawing conclusions about the population based on the sample’s data
