Stats - 2

Question 1

What is the definition of standard error of mean? (SEM)

Answer 1

SD/ root of number of samples

Question 2

How do SD and the number of samples influence SEM?

Answer 2

SD increases, so does SEM

N increases, SEM decreases

Question 3

How do you use SEM to estimate the confidence interval?

Answer 3

confidence interval 95% = mean +/- 2SEM

Question 4

What does ANOVA stand for?

Answer 4

analysis of variance

Question 5

When is ANOVA used?

Answer 5

used for normal distribution, comparison of multiple groups with different sample sizes, numerical data

Question 6

If p<0.05 is found from ANOVA, does that mean all results are significantly different from each other?

Answer 6

not sure - need to do a post-hoc test

Question 7

When estimating the mean in a range of 95% confidence interval, what are the upper and lower boundaries of the mean?

Answer 7

+/- 2SEM

Question 8

What is a post-hoc test?

Answer 8

when ANOVA = p<0.05 - all pairs are checked one by one to find which pairs are significantly different and which aren’t

Question 9

If data is ordinal, what main methods are used to test the hypothesis?

Answer 9

Chi-square

Question 10

In Chi-square analysis, what are the theoretically expected values used to compare with practical data?

Answer 10

Equal percentage or equal sample size from all groups are theoretically same value. Practical value is the value you get from the data

Question 11

In a chi-square, assuming that multiple groups of data are significantly different, does this mean any two of them are significantly different?

Answer 11

No

Question 12

What statistical methods are used with ordinal or nominal data?

Answer 12

Chi-square

non-parametric test

Question 13

In what situations should a non-parametric test be applied with two or more groups of data?

Answer 13

non-normal distribution

use sign or rank as info to compare the groups

Question 14

What are the main differences between parametric and non-parametric tests?

Answer 14

non-parametric - non normal distribution

parametric - normal distribution

Question 15

In non-parametric data, what information or values are used to assess differences between groups of data?

Answer 15

rank

sign

Question 16

When a scatter plot show that two variables have a certain association can we say they are linearly correlated?

Answer 16

no - need to calculate the linear correlation and p value

Question 17

If two variables are linearly correlated, how much significance interval would be expected after a hypothesis test?

Answer 17

p <0.05

Question 18

What range should the correlation coefficient be kept in?

Answer 18

-1

Question 19

IS it possible that the correlation coefficient is negative? what would this mean?

Answer 19

Yes

that an increase in X means a decrease in Y

Question 20

what coefficients are calculated/estimated to produce a regression equation?

Answer 20

b1 and b2
(y = mx+c)
(Y = b2x + b1)

Question 21

What is a residual in linear regression?

Answer 21

the errors between the predicted value and the measured value

Question 22

What does a high or low residual mean?

Answer 22

high - poor quality. the lower value the better

Question 23

Can linear regression methods be extended to non-linear situations? how do we process the original data in such a situation?

Answer 23

Yes - transform non-linear variables into linear variables then use these to construct a linear relation

Question 24

Why does sampling require randomisation?

Answer 24

If not then the samples will not be representative of the bigger population

Question 25

What is the idea behind meta-analysis?

Answer 25

using multi-sourced data to see if it favours one direction - studies would be in the same format and be of high quality

Question 26

What is censored case? what main point shoud be noted when doing this?

Answer 26

survival analysis - requires larger sample size

Question 27

What is statistics?

Answer 27

using a small sample size to find information about a bigger population.