Sources of Variation Flashcards
Define ‘observation’
What we observe (the actual result)
What is the ‘observed value’?
The best estimate of the ‘true’ or ‘underlying’ tendency
What is a ‘hypothesis’?
A statement that an underlying tendency of scientific interest takes a particular quantitative value
What is the ‘p-value’?
The probability of getting an observation as extreme as or more extreme than the one observed, assuming that the stated hypothesis is true.
What can be concluded if p is less than or equal to 0.05?
The data is inconsistent with the hypothesis
There is sufficient evidence against the hypothesis
The hypothesis can be rejected
The observations are statistically significant
What can be concluded if p is greater than 0.05?
Hypothesis is not proven
But it would be reasonable to accept the stated hypothesis
What is the limitation of using p-values to gain ‘significant’ information?
The statistical significance depends on the sample size. 0.05 is an arbitrary value
Why are 95% confidence intervals used?
Results in medical science are subject to variation
What does a 95% confidence interval show?
The range of values within which we can be 95% certain that the ‘true’ value of the underlying tendency lies.
What is the significance of the null hypothesis value being INSIDE the 95% confidence intervals?
p is greater than 0.05
Hypothesis can not be proven. Data is not statistically significant.
What is the significance of the null hypothesis value being OUTSIDE the 95% confidence intervals?
p less than 0.05
The null hypothesis is rejected
The data is statistically significant
How are the 95% confidence intervals calculated?
Lower limit: Observed value/Error factor
Upper limit: Observed value x Error factor
Define ‘tendency’
What we expect to happen
