| Term | Definition |
|---|---|
| chance | Randomness or probability-based selection used in data collection to reduce bias and ensure representativeness. |
| data collection methods | The procedures and techniques used to gather information or data from a population or sample. |
| Term | Definition |
|---|---|
| causal relationships | A relationship between variables where one variable directly causes changes in another variable. |
| experiment | A study in which different conditions or treatments are assigned to experimental units to investigate cause-and-effect relationships. |
| experimental unit | The participants or subjects to which treatments are assigned in an experiment. |
| generalizations | Conclusions or statements about a larger population based on data from a sample. |
| observational study | A study in which treatments are not imposed; investigators examine data from a sample to investigate a topic of interest about the population. |
| population | The entire group of individuals or items from which a sample is drawn and about which conclusions are to be made. |
| prospective | An observational study approach where investigators follow a sample of individuals into the future, collecting data over time. |
| randomly selected | A sampling method where every member of the population has an equal chance of being chosen. |
| representative sample | A sample that accurately reflects the characteristics and composition of the population from which it was drawn. |
| retrospective | An observational study approach where investigators examine data from a sample of individuals based on past information. |
| sample | A subset of individuals or items selected from a population for the purpose of data collection and analysis. |
| sample survey | A type of observational study that collects data from a sample to learn about the population from which the sample was taken. |
| treatment | Different conditions assigned to experimental units in an experiment. |
| variable | A characteristic that changes from one individual to another in a set of data. |
| Term | Definition |
|---|---|
| census | A data collection method that selects all items or subjects in a population. |
| cluster | Concentrations of data usually separated by gaps in a distribution. |
| cluster sample | A sampling method in which a population is divided into smaller groups called clusters, and a simple random sample of clusters is selected, with data collected from all observations in the selected clusters. |
| population | The entire group of individuals or items from which a sample is drawn and about which conclusions are to be made. |
| random number generator | A tool or method used to randomly select items from a population for inclusion in a simple random sample. |
| sample | A subset of individuals or items selected from a population for the purpose of data collection and analysis. |
| sampling method | A specific procedure or technique used to select a subset of individuals from a population for data collection and analysis. |
| sampling with replacement | A sampling method in which an item selected from a population can be selected again in subsequent draws. |
| sampling without replacement | A sampling method in which an item selected from a population cannot be selected again in subsequent draws. |
| strata | Separate groups within a population created by dividing it based on shared attributes or characteristics for stratified sampling. |
| stratified random sample | A sampling method in which a population is divided into separate groups called strata based on shared characteristics, and a simple random sample is selected from each stratum. |
| systematic random sample | A sampling method in which sample members are selected from a population according to a random starting point and a fixed, periodic interval. |
| Term | Definition |
|---|---|
| bias | A systematic tendency for certain responses to be favored over others in a sample, resulting in a sample that does not accurately represent the population. |
| convenience sampling | A non-random sampling method where individuals are selected based on their accessibility or ease of inclusion, introducing potential bias. |
| non-random sampling | Sampling methods that do not use chance to select individuals from the population, introducing potential for bias. |
| nonresponse bias | Bias that occurs when individuals chosen for the sample cannot provide data or refuse to respond, and these individuals differ from those who do respond. |
| question wording bias | A type of response bias caused by confusing or leading questions in a survey or data collection instrument. |
| response bias | Bias that results from problems in the data gathering instrument or process, such as confusing or leading questions. |
| self-reported responses | Data collected directly from individuals about their own characteristics, behaviors, or opinions, which may introduce response bias. |
| undercoverage bias | Bias that occurs when part of the population has a reduced chance of being included in the sample, resulting in an unrepresentative sample. |
| voluntary response bias | Bias that occurs when a sample is comprised entirely of volunteers or people who choose to participate, making the sample unrepresentative of the population. |
| Term | Definition |
|---|---|
| blocking | A technique that groups experimental units into blocks where units within each block are similar with respect to at least one blocking variable. |
| blocking variable | A variable used to group experimental units into blocks so that natural variability can be separated from differences due to that variable. |
| completely randomized design | An experimental design where treatments are assigned to experimental units completely at random to balance the effects of confounding variables. |
| confounding variable | A variable that is related to the explanatory variable and influences the response variable, potentially creating a false perception of association between them. |
| control group | A group in an experiment that receives no treatment or a standard/baseline treatment, used as a reference for comparison. |
| double-blind experiment | An experiment where neither the subjects nor the members of the research team who interact with them know which treatment a subject is receiving. |
| experimental unit | The participants or subjects to which treatments are assigned in an experiment. |
| explanatory variable | A variable whose values are used to explain or predict corresponding values for the response variable. |
| factor | An explanatory variable in an experiment whose levels are manipulated intentionally. |
| matched pairs design | A special case of a randomized block design where subjects are arranged in pairs matched on relevant factors, and each pair receives both treatments. |
| participant | Human subjects or individuals who are assigned treatments in an experiment. |
| placebo | An inactive substance given to a control group to determine if a treatment of interest has an effect. |
| placebo effect | A response to a placebo that occurs when experimental units react to receiving a treatment, even though the treatment is inactive. |
| random assignment | The process of randomly allocating experimental units to different treatment groups to ensure unbiased distribution and reduce bias. |
| randomized complete block design | An experimental design where treatments are assigned completely at random within each block to control for a blocking variable. |
| replication | The use of multiple experimental units in each treatment group to increase reliability and reduce the effect of random variation. |
| response variable | A variable whose values are being explained or predicted based on the explanatory variable. |
| single-blind experiment | An experiment where subjects do not know which treatment they are receiving, but members of the research team do, or vice versa. |
| treatment | Different conditions assigned to experimental units in an experiment. |
| treatment groups | Distinct groups in an experiment that receive different treatments or conditions being compared. |
| Term | Definition |
|---|---|
| experimental design | A structured plan for conducting an experiment that specifies how treatments will be assigned to experimental units and how data will be collected. |
| experimental unit | The participants or subjects to which treatments are assigned in an experiment. |
| Term | Definition |
|---|---|
| experimental unit | The participants or subjects to which treatments are assigned in an experiment. |
| generalize | The process of extending conclusions from an experiment conducted on a sample to a larger population. |
| random assignment | The process of randomly allocating experimental units to different treatment groups to ensure unbiased distribution and reduce bias. |
| random sampling | A method of selecting samples from a population where each member has an equal chance of being chosen, ensuring the sample is representative of the population. |
| representative | A characteristic of a sample that accurately reflects the key features and distribution of the larger population from which it was drawn. |
| statistical inference | The process of drawing conclusions about a population based on data collected from a sample. |
| statistically significant | A result indicating that an observed difference is large enough that it is unlikely to have occurred by chance alone. |
| treatment | Different conditions assigned to experimental units in an experiment. |