Statistics Flashcards
What is sampling?
randomnly take a small set of data from a huge set to be investigated
What are the two aspects of sampling?
randomisation and size
What are the two types of samples?
Independent or dependent
How to decide a population size?
depends on the research aim
What information is needed to estimate sample size?
clinical difference in practice
standard deviation from previous/pilot studies
How to decide sample size?
difference in means of 80% in medical research
0.05 significance level
Ideal sample size
larger than 10 and ideal is 30
What is a double blind experiment?
nobody knows what the f is going on
How do we know if data is normal distribution?
skewness coefficient, >2EM means its not normal distribution
P-p plot- dots arent around the line its not normal distribution
Kolomogorov-smirnov- if the significance is below 0.05 its not normal distribution
What is the null hypothesis?
G1 and G2 arent stastically different
If the tested results are <0.01 or 0.05 then reject the null hypothesis
When do you accept the null hypothesis?
p>0.05
what is the t-test?
parametric test with a parameter similar to normal distribution
used to compare two groups of data
what is an applied situation for a t-test
to compare means for two groups of data with small sample size or data distribution should be normal
When is ANOVA used?
when more than two means are compared with one another, if its just two then the t-test is used
what is degree of freedom?
n-1
what is variance?
descriptor to show how far away samples are from the data center
standard deviation squared
what is an independent sample t-test?
two samples from different populations regarding the same variable
what is paired t-test?
two sample means from the same population measuring the same variable at two different times e.g. pre and post test
what is variance?
similar to standard deviation and is a descriptor to show how far away the data is from the center
standard deviation squared
what are the two variances?
variance within group shows differences amongst samples and variances between groups shows differences between groups
what is the mean of squared differences between groups and within groups
between groups= differences between group mean and total mean
within groups= between samples and their group mean
what is the F value?
ANOVA uses the F value to test if p value is significant
MS between groups/ MS within groups = f value
What are the two test before/after ANOVA?
before- contrast
after- post-hoc
how do we describe non-numeric data?
nominal and ordinal data
frequencies, percentages, distribution, charts- pie, bar, histogram, tables etc.