Bio 180: Statistical Methods in Biology - How to Collect Data PDF

Eric Zeus C. Rizo Ph.D. Bio 180: Statistical Methods in Biology How do we collect data? Going back to basics: The Scientific Method Answering Scientific Inquiry Sources of Statistical Data Sources of Statistical Data: Primary VS Secondary Primary Data Primary data means first-hand informat...

Eric Zeus C. Rizo Ph.D. Bio 180: Statistical Methods in Biology How do we collect data? Going back to basics: The Scientific Method Answering Scientific Inquiry Sources of Statistical Data Sources of Statistical Data: Primary VS Secondary Primary Data Primary data means first-hand information collected by an investigator. It is collected for the first time. Usually more reliable. Secondary Data Secondary data refers to second-hand information. It is not originally collected and rather obtained from already published or unpublished sources. Metadata/Meta-Analysis VS Systematic Review VS Literature Review Meta-Analysis Combine data from multiple studies to produce a single, more precise estimate of an effect, essentially providing a quantitative synthesis of the findings. Systematic Review comprehensively identifying, evaluating, and summarizing all available research on a specific topic aimed at answering a specific research question. Literature Review Provides a general overview of research on a topic, often including a variety of sources with varying levels of quality. Sources of Data: External VS Internal External Data When data is collected from sources outside the organization/study/resear ch project, etc. Internal Data When data is collected from reports and records of the organization/study/resear ch project, etc. itself Sampling and Sampling Techniques What is Sampling? Sampling allows you to test a hypothesis about the characteristics of a population. Sampling techniques are based on the nature of the aims/objectives/research questions of a study Validity of Samples Internal vs. External Validity Internal validity refers to the degree of confidence that the causal relationship being tested is trustworthy and not influenced by other factors or variables. External validity refers to the extent to which results from a study can be applied (generalized) to other situations, groups, or events. Sampling Bias Sampling bias occurs when some members of a population are systematically more likely to be selected in a sample than others. It limits the generalizability of findings because it is a threat to external validity, specifically population validity. An easy way of avoiding sampling bias is to oversample. Sampling Techniques Sampling Techniques/Methods refers to how a sample is chosen from a population Key points to consider when selecting a sampling technique: Research objectives: What are you trying to learn from your study? Population characteristics: Is your population homogenous or diverse? Accessibility of the population: How easy is it to reach members of your population? Budget and time constraints: How much time and money do you have for data collection? Sampling Techniques Probability Sampling ensures every population member has a chance of being selected Non-Probability Sampling selection not based on random chance (i.e. specific criteria in choosing individuals from a population Probability Sampling Simple Random Sampling Each individual has an equal chance of being chosen. Systematic Sampling Selecting every nth individual from a list Stratified Sampling Dividing the population into subgroups (strata) and randomly selecting from each Cluster Sampling Randomly selecting clusters (groups) from the population and sampling all individuals within those clusters (Instead of sampling individuals from each subgroup, you randomly select entire subgroups) Non-Probability Sampling Convenience Sampling Selecting participants who are easily accessible Purposive Sampling Deliberately selecting individuals with specific characteristics relevant to the study Snowball Sampling Asking participants to refer other potential participants Quota Sampling Selecting a specific number of individuals from different subgroups to ensure representation Other considerations in choosing a sampling technique Probability vs. Non-probability sampling: Probability methods allow for generalizations to the population, while non- probability methods (like convenience sampling) may not. Sample size calculation Determine the appropriate sample size to achieve the desired level of statistical power. Ethical considerations Ensure your sampling method is fair and does not introduce bias. Research/ Study Design The importance of an appropriate study/research design The research design refers to the overall strategy that you choose to integrate the different components of the study in a coherent and logical way Elements of research design Research question: The question that the research is trying to answer Theories and models: The theories and models that the research is based on Data collection: The plan for gathering data from participants or sources Data analysis: The plan for analyzing the data using statistical or analytical techniques Reporting: The plan for reporting the findings from the data analysis Types of Research Design Quantitative Measure different types of variables and describe frequencies, averages, and correlations Test hypotheses about relationships between variables Test the effectiveness of a treatment Tend to be more fixed and deductive, with variables and hypotheses clearly defined in advance of data collection. Types of Research Design Qualitative Understand subjective experiences, beliefs, and concepts Gain in-depth knowledge of a specific context or culture Explore under-researched problems and generate new ideas Tend to be more flexible and inductive, allowing you to adjust your approach based on what you find throughout the research process. Methods of Collecting Data Some Methods for Collecting Biological Data Survey Methods questions are asked to obtain information Observation/Monitoring Methods makes possible the recording of behavior/data but only at the time of occurrence with no interference from the researcher Experimental Methods A method designed for collecting data under controlled conditions. An experiment is an operation where there is actual human interference with the conditions that can affect the variable under study. Use of Existing Studies Collecting data from existing data sources (secondary data) Things to consider in choosing methods in collecting data Research goals Target audience Type of data needed Available resources The nature of the research question Sample size Feasibility Ethical implications Level of detail required Assignment for Next Meeting  THANK YOU! Clarifications and other questions?