Stats 2

Question 1

what is a study

Answer 1

research project an investigation or a clinical trial, basically anything where there are research questions to be answered

Question 2

what are observational studies

Answer 2

record outcomes as they have occurred and there is no attempt to modify the frequency of their occurrence.

Question 3

what are experimental studies

Answer 3

involve investigators introducing or removing an exposure e.g. treatment or intervention to test relationships between exposures and outcomes. Investigators have direct control over the study conditions and exposure status.

Question 4

Simple observational studies

Answer 4

information collected and the researcher has access to this and is able to decide on the analysis

however

has no control over which units receive which exposures

Question 5

Simple experimental study

Answer 5

The researcher controls how units are allocated exposures so they

have a number of units available

can decide on what is to be investigated and how

can determine the method of allocating exposures to units

Question 6

What should the statistical design of a study be matched too

Answer 6

they should be matched to the objectives of

optimizing resources

getting accurate and precise results

Question 7

what is the consequence of a small study

Answer 7

we may miss worthwhile effects

Question 8

what is the consequence of a large study

Answer 8

wastes resources

Question 9

what is the size of sample a function of

Answer 9

effect size we are looking for

variability of the end point

significance level

power

Question 10

what is replication

Answer 10

defines how many units receive the same exposure level

Question 11

what does increasing the replication do

Answer 11

improves accuracy of results and is essential to provide estimates of precision and it generally increases the power of the experiment to detect important differences between exposure levels

Question 12

What is pseudo replication

Answer 12

examing leaves on the same plant is psuedo replication

Question 13

what is blocking

Answer 13

used to take account of differences in heterogeneities such as male female old you etc

Question 14

what does blocking improve

Answer 14

precision

Question 15

what is vital for the results of an experiment to be meaningful

Answer 15

randomization as it allows a fair comparison to be made between exposures

Question 16

what do all investigations allow us to answer

Answer 16

a hypothesis

Question 17

what is null hypothesis denoted as

Answer 17

H0

Question 18

what is the alternative hypothesis denoted as

Answer 18

H1

Question 19

what is a type 1 error

Answer 19

error we make if we reject the null hypothesis when it is true

Question 20

what is a type 1 error often denoted by

Answer 20

greek letter a

Question 21

what is a type 2 error

Answer 21

is an error we make if we do not reject the null hypothesis when in fact it is false

Question 22

what is a type 2 error often denoted by

Answer 22

greek letter B

Question 23

what is the goal of hypothesis testing

Answer 23

minimize the types 1 error and minimize type 2 error