Data Collection Principles and Sampling Methods

Anecdotal Evidence

Unusual observations inspiring study design, not conclusions.

Weight Loss Success

Stories of diet success, not universally applicable.

Data Collection

Higher data volume reduces bias and increases coverage.

Descriptive Statistics

Identifies and prevents reliance on anecdotal data.

Hypothesis Testing

Determines statistical significance of test results.

Sampling

Practical method to gather manageable data.

Representative Sample

Sample characteristics should match population characteristics.

Simple Random Sample

Equal chance for each sample size selection.

Stratified Random Sample

Samples taken from distinct groups within a population.

Cluster Random Sample

Selects random clusters and includes all members.

Systematic Sample

Selects every kth member after a starting point.

Convenience Sample

Easily obtainable samples, prone to bias.

Sampling Bias

Error introduced by non-representative sampling methods.

Exploratory Data Analysis

Analyzes data to summarize its main characteristics.

Statistical Significance

Probability that results are not due to chance.

Population

Entire group from which samples are drawn.

Strata

Subgroups within a population for stratified sampling.

Clusters

Groups formed for cluster sampling methodology.

kth Member

Every k-th individual selected in systematic sampling.

Data Aspects Coverage

Comprehensive representation of data features.

Cost-Effective Sampling

Sampling method that minimizes costs while gathering data.

Multistage sampling

Combines multiple sampling methods for data collection.

Stratified sampling

Samples within distinct job categories for accuracy.

Observational study

Researchers observe without interfering in data collection.

Designed experiment

Researchers influence data by assigning treatments.

Causal connection

A direct relationship indicating one variable affects another.

Control

Selecting a representative sample to minimize extraneous variables.

Randomization

Assigning participants randomly to balance treatment groups.

Blocking

Grouping individuals by attributes before random assignment.

Gallup Organization

Conducts surveys using multistage sampling for elections.

Transgenic mice study

Experiment measuring cancer risk from cell phone radiation.

Brain tumor rate

Incidence of tumors in exposed versus unexposed mice.

Cell phone radiation

Microwave emissions potentially linked to health risks.

Response variable

Outcome measured in an experiment to assess effects.

Extraneous variables

Uncontrolled factors that may influence study results.

Sample size

Number of participants in a study, e.g., 1500 employees.

Survey methodology

Approach to collecting data from a specific population.

Data collection methods

Techniques used to gather information for analysis.

Statistical data processing

Analyzing data to derive meaningful insights.

Job categories

Different roles within a company affecting software use.

Health risk assessment

Evaluating potential dangers associated with cell phone use.

Association evidence

Indications of a relationship between two variables.

Experimental condition

Specific treatment applied to subjects in an experiment.

Replication

Number of distinct units under same treatment.

LEAP Study

Study involving infants with eczema and allergies.

Randomization

Ensures equal gender proportion in treatment groups.

Cohorts

Blocks based on skin test results for infants.

Observational Study

Observes population and records future outcomes.

Nurses' Health Study

Prospective study tracking chronic disease risk factors.

Retrospective Study

Observes past outcomes using current sample data.

Premature Birth Study

Compares school performance of premature vs full-term children.

Sampling Bias

Occurs from nonrandom samples lacking population representation.

Nonresponse Bias

Results from subjects refusing or failing to respond.

Response Bias

Incorrect responses due to confusing question wording.

Confounding Variable

Unmeasured variable affecting both explanatory and response variables.

Sunscreen and Skin Cancer

Study linking sunscreen use with skin cancer incidence.

Sun Exposure

Confounding variable affecting sunscreen use and skin cancer.

Exercise and Stress Levels

Negative correlation between exercise and stress observed.

Sleep Patterns

Potential confounder affecting exercise and stress relationship.

Sample Survey

Method of collecting data from a population sample.

Data Collection

Gathering information through surveys or experiments.

Stratification

Dividing subjects into subgroups for analysis.

Outcome Recording

Documenting specific results from observational studies.

Follow-up Contact

Reaching out to nonrespondents for better data.

Research Design

Plan to ensure validity of study results.