Unit 3.3 - reporting & critical eval. Flashcards
Two types of variation?
discrete
continuous
Describe ‘Normal distribution’
Bell-shaped curve
Most common distribution in nature
Symmetrical
Give an example of a pattern that shows normal distribution
Height of humans
What are the two types of skewed distribution?
Negative and Positive
Describe ‘Skewed Distribution’
Can be negative or positive
Mean is not the most common value
Most common value is not central
Give an example of skewed distribution
The age of deaths (skewed to 70-80 years)
What should a representative sample have?
Same mean and degree of variation about the mean as the population as a whole
What should be considered when assessing precision and accuracy?
Mean of replicated measurements
Variation in these replicated measurements
Number of samples tested
How regularly measurement equipment requires calibration
What is a confidence interval?
Statistical estimate of range of values within a certain percentage of the total population would be found
What is a statistically significant result?
One in which the difference between groups is unlikely to be due to chance alone
What p value shows the results are statistically significant?
0.05
What are the two types of control groups?
negative and positive
What does a negative control group do?
Provide data for what happens in the absence of a treatment
What controls should be used to test for false positive results?
negative
What do positive control groups prove?
The experimental design can detect a change in the dependent variable when one occurs
