Chapter 1 Data Collection Flashcards
STATISTICS
The science of collecting, organizing, and analyzing information to draw conclusions or answer questions.
It is also about providing s measure of confidence in any conclusions.
DATA
Facts or propositions used to draw a conclusion or make a decision.
Describe characteristics of an individual.
POPULATION
The entire group to be studied
SAMPLE
A subset of the population being studied
INDIVIDUAL
A person or an object that is a member of the population being studied
STATISTIC
A numerical summary of a sample
DESCRIPTIVE STATISTICS
The organizing and summarizing of data through numerical summaries, tables, and graphs, without making any general conclusions about the population
INFERENTIAL STATISTICS
Uses methods that take a result from a sample, extend it to the population, and measure the reliability of the result (level of confidence)
PARAMETER
A numerical summary of a population
VARIABLES
The characteristics of the individuals in a study
QUALITATIVE (CATEGORICAL) VARIABLES
Classify individuals based on some attribute
QUANTITATIVE VARIABLES
Numerical measures of individuals. Values can be added or subtracted.
DISCRETE VARIABLE
A quantitative variable that has either a finite or countable number of possible values
CONTINUOUS VARIABLE
A quantitative variable that has an infinite number of possible values that are not countable.
Typically results from a measurement.
OBSERVATIONAL STUDY
Type of study in which the researcher observes happenings, measures things of interest, and draws conclusions
EXPERIMENTAL STUDY
Type of study in which the researcher manipulates a variable, tries to determine how the manipulation affects other variables (treatment group, control grpup)
CENSUS
A survey of each and every member of a population
NONRESPONSE
Respondents can choose not to be contacted or not to answer
UNDERCOVERAGE
Refers to people in a population that have absolutely no chance of being included in the sample
CONFOUNDING
Occurs when the effects of two or more explanatory variables are not separated
LURKING VARIABLE
An explanatory variable that was not considered in a study but that affects the value of the response variable
CROSS-SECTIONAL STUDY
An observational study that collects information about individuals at a specific point in time or over a very short period of time
3 TYPES OF OBSERVATIONAL STUDIES
Cross-Sectional (point in time or short period of time)
Case-Control (retrospective; paired groups)
Cohort (selected group over time; prospective)
CASE-CONTROL STUDY
An observational study that is retrospective; requiring individuals to look back in time or the researcher to look at existing records.
Individuals that have certain characteristics are paired with those that do not.
COHORT STUDY
An observational study that follows a selected group (cohort) over a period of time, during which characteristics are recorded.
Because data are collected over time, cohort studies are prospective.
ADVANTAGE OF CASE CONTROL STUDIES
The Control group allows for comparison
DISADVANTAGES OF CASE-CONTROL STUDIES
- Individuals must remember details
2. Records might not exist
ADVANTAGE OF COHORT STUDIES
The researcher doesn’t need to rely on the memory of participants or existing records
DISADVANTAGES OF COHORT STUDIES
- Time and labor-intensive
2. Can be expensive
EXAMPLE OF A COHORT STUDY
The Framingham Study
RANDOM SAMPLING
The process of using chance to select individuals from a population to be included in a sample
SIMPLE RANDOM SAMPLING
A sample of size n is obtained from a population of size N, if every possible sample size n has an equal chance of occurring
FRAME
A list of all the individuals in the population of interest
SAMPLING WITHOUT REPLACEMENT
An individual who is selected from the population to be in the sample cannot be selected again
STRATIFIED SAMPLE
A sample obtained by dividing the population into nonoverlapping groups (strata) then obtaining a simple random sample from each stratum.
The individuals in each stratum should be homogeneous in some way.
ADVANTAGE OF STRATIFIED SAMPLING
The researcher can determine characteristics within each stratum, which allows an analysis to be performed to determine whether any significant differences exist among them.
SYSTEMATIC SAMPLE
A sample obtained by selecting every kth individual from the population. The first individual selected corresponds to a number between 1 and k.
Does not require a frame
ADVANTAGES OF SYSTEMATIC SAMPLING
- Useful when researcher cannot gather a list of all the individuals in a population
- Typically provides more info for a given cost than simple random sampling
- Easier to employ, so less likelihood of of interviewer error occurring
CLUSTER SAMPLE
A sample obtained by selecting all of the individuals within a randomly selected collection or group of individuals
CONVENIENCE SAMPLING
A sample in which the individuals are easily obtained and not based on randomness
MULTISTAGE SAMPLING
Sampling, usually for large-scale surveys, that uses a combination of techniques
SAMPLING BIAS
Occurs when the technique used to obtain the sample’s individuals tends to favor one part of the population over another
NONRESPONSE BIAS
Occurs when individuals selected to be in a sample who do not respond to the survey have different opinions than those who do
RESPONSE BIAS
Occurs when the answers on a survey do not reflect the true feelings of the respondent
TYPES OF RESPONSE BIAS
- Interviewer error
- Wording of questions
- Ordering of questions or words
- Type of Question (open or closed)
- Data or entry error
METHODS TO IMPROVE NONRESPONSE
- Callbacks
- Using rewards or incentives
NONSAMPLING ERRORS
- Undercoverage
- Nonresponse bias
- Response bias
- Data entry error
- Incorrect answers to questions
SAMPLING ERRORS
Results from using a sample that gives incomplete information about a population
