Bruno
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09.10.03 (4 years ago)
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Hi,
This is not what you have asked for, but nevertheless few points from Biostatistics
1. Assume that you are measuring BP after giving a new anti hypertensive a SAME GROUP........... The experiment can be done in a lot of ways..............You take a BP.... give the drug.... take a BP again........ If the variations are compared it is PAIRED t Test...... Or if you measure the BP of a medical student before and after a case presentation !!!!
2. You measure BP of few surgeons.... You measure BP of few physicians..... You compare the BP of the two groups.......... Thi is UNPAIRED t Test
{But if you measure the BP in the "same" group, before and after intervention, it is paired..........}
3. You measure BP in groups of people.where the number of groups is mroe than 2 ........ say........ surgeons, physicians, orthopaedics
paedicians, Anaesthetists etc.......... Here we use One way ANOVA....... ANOVA is Analysis of Variance Test
4. Now you measure BP as well as Heart Rate in a group of peoplesay........ surgeons, physicians, orthopaedics
paedicians, Anaesthetists etc.......... Here we use Two way ANOVA.......
Let me give another example
1. The Exam marks of boys are analysed......... One is a mark after few days holidays and another is a mark of a exam conducted immediately after a cultural event.... This is Paired T Test
2. Suppose you analyse the marks of boys as well as girls............. it is un paired t test
3. Suppose you analyse the marks of hostel boys, hostel girls, day scholar boys, day scholar girls ( > 2 groups) it is One way ANOVA
4. Suppose you analyse the marks of hostel boys, hostel girls, day scholar boys, day scholar girls ( > 2 groups) in more than one way, say a written exam and a orals, it is Two way ANOVA
Please tell me whether you have understood or not............. If the subject is still unclear, we will follow it by a detailed explanation
1.Student's t- TEST was introduced by W.S.Gosset whose pen name was Student and it is the same t test we normally refer to
2.F test is ANOVA
3.One tailed and two tailed........... Suppose you are comparing two samples... for example marks in Anatomy
and Marks in SPM of a group of studnets.......... In a normal class Anatomy
marks will be more than SPM !!!! (Isn't it ??) But we have to find whether the increased marks in Anatomy
is a real increase or a chance..... So in conditions where we check in one direction only we use one tailed test
If higher or lower are not specified, we use two tailed tests
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