A divergence, due to chance alone, of an observation on a sample from the true population value.
What does error lead to?
imprecise results
Define precision.
little variation between the results
What is sampling error?
occurs as a part of the processes of selecting study participants
What are the 6 steps to health research?
1. define a question
2. sample
3. measure
4. intervene
5. describe/analyze relationships
6. make inferences
Define Inference.
Applying observations of study sample to the entire source population
What is systematic error? (2)
error resulting from flaw either in the method of selection of study participants or in the procedures for gathering relevant exposure and/or disease information
affects every singe participants data
Define validity.
The degree to which measurement measures what is meant purports to measure
Why is it good to survey a larger sample size?
It better represents the population
As sample size INCREASES, Random error __________.
decreases
What is significant about systematic error aka Bias? (3)
results tend away from the truth systematically
cannot be addressed with analysis
flaw in study design
Error can affect the _______ and ________ of results.
accuracy
precision
Define accuracy.
when observed result is close to the truth value
precision results in?
low random error
accuracy results in?
low systematic error
True or False. The greater our sample size, the less likely we are to see systematic error. (2)
False, happens in the outset
error happens to every participants data
What is selection bias?
occurs when there is a systematic difference between the characteristics of people selected for a study and the characteristics of those who are not.
What is selection bias categorized into?
systematic error in selecting study participants
What are the selection bias in cross sectional studies?
survivor bias
volunteer bias
Define survivor bias. (2)
aka incidence/prevalence
when survivors being surveyed or studied are not representative of the entire diseased population