Revision Flashcards
lecture 11
What is the hypothetico-deductive method?
proposed discription of the scientific method.
What are the key steps of the hypothetico-deductive method?
- Observation
- Model
- Hypothesis
- Experiment
- Result reporting
Why is it usefull to establish an alternate and null hypothesis before you experiment?
Null hypothesis - know what you will reject or accept
Idicates the question or direction effect if we can reject our null hypothesis we can accept an alternative one. t-tests and tail tests.
What is an independant variable?
The variable that you control and manipulate.
What is the dependant variable?
The variable that you measure.
What is the confidence interval?
95% confidence level in the middle in two tailed tests.
way to express the precision of the estimate of the population.
How do we reliably estimate population parameters?
Randomisations - avoiding bias
Replication - more reliable and allows repetition
Control - shows what we are measuring is what actually is being changed.
What is central tendency?
summary to measure a whole set of
What do we use to measure the central tendency of parametric data?
The mean
What do we use to measure the central tendency of non-parametric data?
Mode and median
Why is a normal distribution advantageous?
What is the central limit theorem?
What 4 things affect the power of statistical tests?
- Sample size
- variability of data
- magnitude of the difference between sample means
- Type 1 error probability
What is a type 1 error?
False positive - rejecting the null hypotheses
What is a type 2 error?
False negative - accepting the null hypotheses
comparing 2 independant samples?
Samples
for parametric data = t-test
for non-parametric data = mann-Whitney U-test
comparing 2 non-independant samples?
Paired samples
for parametric data = paired t-test
for non-parametric data = Wilcoxon text
One tailed test
H0- No difference between the two groups.
HA- Mean on one group is larger or smaller than the other.
Two tailed test
H0- No difference between the two groups.
HA- Mean of one group is different to the other group
What are the 4 assumptions of the t-test?
- follow continuous or ordinal distribution
- Smaples are independant of eachother
- follow normal distribution
- variance is the same
What is the Levene’s test?
Test for equal variance
before the independant t-test
p>0.05 - equal
p<0.05 - unequal
