Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
PHC 6013: Validity
Validity - precision and bias
| Question | Answer |
|---|---|
| What is bias? | Any process at any stage of inference which tends to produce results or conclusions that differ systematically from the truth |
| What is accuracy? | The degree to which a variable actually represents what it is intended to represent |
| Accuracy is a function of what? | It is a function of systematic error (bias); the greater the error, the less accurate the variable. |
| What is the best way to assess accuracy? | Comparison with a reference standard |
| What is the benefit of higher accuracy in a study? | Increases validity of conclusions |
| What is accuracy threatened by? | Systematic error (bias) contributed by: observer, subject, instrument |
| What are the three main classes of measurement error? | Observer, instrument, and subject bias |
| What is a "gold standard"? | A reference technique that is considered accurate |
| What are the major approaches to increasing accuracy? | 1) Standardizing the measurement methods 2) Training and certifying the observers 3) Refining the instruments 4) Automating the instruments 5) Making unobtrusive measurements 6) Calibrating the instruments 7) Blinding |
| Does blinding ensure the overall accuracy of measurements? Explain. | No, but it can eliminate differential bias that affects on study group more than another. |
| What is the difference between validity and accuracy? | Validity is a particular type of accuracy that measures how well a measurement represents phenomenons of interest that are subjective and abstract, such as pain or quality of life, for which there is no concrete or gold standard. |
| What is content validity? | How well the assessment represents all aspects of the phenomena under study and often uses subjective judgments about whether the measurements seem reasonable |
| What is face validity? | Subjective judgments; essentially, researchers are simply taking the validity of the test at face value by looking at whether a test appears to measure the target variable |
| WHat is construct validity? | How well a measurement conforms to theoretical constructs |
| What is criterion-related validity? | The degree to which a new measurement correlates with well-accepted existing measures |
| What is predictive validity? | Related to the criterion-related approach to assessing validity, it is the ability of a measurement to predict an outcome |
| What are the three ways to view and assess validity? | Content, construct, and criterion-related |
| What describes phenomena in terms that can be analyzed statistically? | Measurements |
| What does the validity of a study depend on? | How well the variables designed for the study represent the phenomena of interest |
| What enhances the validity of drawing inferences from the study to the universe? | Minimizing measurement error by designing measurements that are relatively precise and accurate |
| What is the degree to which a variable is reproducible, with nearly the same value each time it is measured? | Precision |
| What has a very important influence on the power of a study? | Precision |
| What is the relationship between precision and power? | The more precise a measurement, the greater the statistical power at a given sample size to estimate values and to test hypotheses |
| What are some other terms for precision?: | Reproducibility, reliability, consistency |
| Precision is a function of what? | It is a function of random error (chance variability); the greater the error, the less precise the measurement. |
| What is systematic error also called? | Bias |
| What is random error also called? | Chance variability |
| What are the three main sources of random error in making measurements? | Observer, instrument, and subject variability |
| How is precision assessed? | Through the reproducibility of repeated measurements, either comparing measurements made by the same person/instrument (within-observer/instrument reproducibility) or different people (between-observer/instrument reproducibility). |
| What is within-observer reproducibility? | Measurements made by the same person/instrument |
| What is between-observer reproducibility? | Measurements made by different person/instrument |
| What are the major approaches to minimizing random error and increasing the precision of measurements? | 1) Standardizing the measurements 2) Training and certifying the observers 3) Refining the instruments 4) Automating the instruments 5) Repetition |
| What strategies should always be used to increase precision of a study? | 1) Standardizing the measurements 2) Training and certifying the observers |
| What is guaranteed to improve precision whenever feasible and affordable? | Repeating the measurement |
| What is precision? | The degree to which a variable has nearly the same value when measured several times. |
| What is the best way to assess precision | Comparison among repeated measures |
| What is the benefit of higher precision in a study? | Increased power to detect effects |
| What is precision threatened by? | Random error (chance) contributed by: observer, subject, instrument |
| What are the sources of systematic error? | 1) Selection bias 2) Information bias 3) Confounding |
| What type of bias is easier to prevent and measure? | Information biases (compared to sampling biases) |
| What are sources of threats to internal validity? | 1) Error 2) Bias 3) Confounding |
| What is the consequence of selection bias? | The association between exposure and outcome among those selected for analysis differs from the association among those eligible. |
| What types/sources of biases fall under selection bias? | 1) Bias resulting from inappropriate selec- tion of controls in case-control studies 2) Bias resulting from differential loss-to-follow up 3) Incidence–prevalence bias 4) Volunteer bias 5) Healthy-worker bias 6) Nonresponse bias. |
| What are the stages of research in which bias can occur? | 1) Literature review 2) Specifying and selecting the study sample 3) Applying the intervention (for experimental) 4) Measuring exposures and outcomes 5) Analyzing the data 6) Interpreting the analysis 7) Publishing the results |
Created by:
AlneciaPHS
Popular Health & Social Care sets