Data analysis 3

Question 1

Formulating a null hypothesis

Answer 1

There is no statistical significant difference between a serum testosterone in male athlete with conc of greater than 50 microgram/ millilitre and male athlete sprinting speed of male athlete serum conc of less than 50 mp/ml

Question 2

Is the difference observed significant.

Answer 2

p<a>a not significant difference</a>

Question 3

Comparing mean value, standard deviation , p value(parametric data).

Answer 3

bigger the difference in mean = smaller the. p value (data is significant)
if mean and SD are same between two groups but the p value is different, the group with smaller P value had more samples (more likely to find significant difference in a larger data)

Question 4

comparing non parametric data by running a mann whitney U test

Answer 4

• the difference in mean doesn’t show significant data because non parametric tests don’t compare data to a mean.
• they rank data and look at difference between two numbers , so you dont look at data with big difference in numbers but look at numbers closer to each other so they will have a smaller difference so smaller p value showing significance.

Question 5

to identify parametric and non parametric data what graph do you use

Answer 5

• histogram an QQ plot
• QQ plot shows if there is normal distribution there should be spread of data along line of best fit.
• normal bell curve(around histogram) = parametric

Question 6

p value and histogram that shows significant deviation to be paired or unpaired , parametric or non parametric

Answer 6

• non parametric : doesn’t follow normal distribution
• paired bc the same group of people used before and after
• so you uses wilcoxon signed Rank

Question 7

What are null and alternative hypothesis tested by ANOVA in the study

Answer 7

• looks at any difference between any different groups
• ANOVA null: there will be no significant difference between any groups
• ANOVA alternative : there will be a significant difference between the groups

Question 8

Anova test result

Answer 8

• lots of numbers to show the computer system test is working but the only thing you are interested in is the p value
• p value > alpha (0.05), accept null , no significant difference
• p <a></a>

Question 9

Two way ANOVA

Answer 9

• level of depression of patients that have anxiety or not
• and is there a difference of patients treated with those different drugs
• interaction effect: between patients with anxiety or not and efficacy of drug

Question 10

Categorical vs continuous variables

Answer 10

categorical : one or the other , male or female

continueos: take any value, height, weight.

Question 11

fishers exact test:

Answer 11

tests if there are non random associations between two categories.

Question 12

How does chi-squared test work?

Answer 12

compare one group with the rest of the different group,
so E vs A , E vs B, E vs C, E vs D
work out p value for each one

Question 13

Why bonferroni correction is limited?

Answer 13

• dont wanna do too many comparison bc you are more likely to get error
• reduce false positive (type 1 error)
• Tukey’s and Dunnett’s reduce error rates mathematically.