1. Parametric hypotheses tests
Marek Majdan
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;

2. Principle of hypothesis tests
Null and alternative hypothesis
Statistical tests used to reject or accept these hypotheses and infere results from a sample to the population
Every test has his own hypothesis
Choice of test depends on data
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;

3. T test One sample (compares sample mean with population mean)
Two independent samples (compares means of two samples)
Paired (compares means of repeated measurements in the same sample)
Null hypothesis: compared means are equal
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;

4. T test in R
2 independent groups t-test t.test(y~x) - where y is numeric and x is a binary factor
2 independent groups t-test t.test(y1,y2) - where y1 and y2 are numeric
Paired t-test t.test(y1,y2,paired=TRUE) - where y1 & y2 are numeric
One samle t-test t.test(y,mu=3) – where mu is the population mean
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;

5. ANOVA test To compare means of three or more groups Null hypothesis:
the compared means are equal
In R:
summary(aov(variable~grouping variable, data=database name))
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;

6. Post hoc test
Anova only tells us that at least two of the compared means are equal
Post hoc test compares mean of each group with each
Tukey honest significance test
results=TukeyHSD(aov(ar_lv~sampleNO, data=zoltan));results
Other tests: paired t test with corrections
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;

7. Comparing proportions
Chi squared test to compare proportions between categories of a 2x2 table, 2xN table or MxN table
In R:
chisq.test (table)
prop.test (table)
Training in essential biostatistics for Public Health Professionals in BiH, Marek Majdan, PhD;