RCT Class #8

Question 1

most basic type of randomization and define it

Answer 1

simple randomization

assign patients to one of two groups, individuals are chosen at random and has the same probality of being chosen but they are not randomly assigned to an intervention.

Question 2

What does it mean to say individuals are chosen at random but are not randomly assigned to an intervention.

Answer 2

They are chosen from the population to be a candiate for the study so therefore not randomly chosen for an intervention

Question 3

website he likes for rct

Answer 3

randomization.com

Question 4

What is blocked randomization?

Answer 4

randomize with short blocks, to account for changing baseline characteristics over time

Question 5

typical block size

Answer 5

4, 6, or 8

Question 6

PRos of block randomization

Answer 6

1. avoids imbalances in allocation
2. if trial stops early, balance is nealy s\assured
3. Protects against participatnchanges over time

Question 7

what is a simple random sample

Answer 7

for a population selected each individual has the same probability of being chosen.

Question 8

What type of randomization do we need for our prop

Answer 8

stratified randomization with randomly permuted blocks (blocks size are random)

Question 9

How to avoid problems with randomization

Answer 9

after first round have someone validate it.

Question 10

What is the problem with simple randomization

Answer 10

patients characteristics change over time, this may casuse imbalances and serious bias.

Question 11

Blocks are set ratio’s

Answer 11

yeah, that way we protect against things going out of control with balance

Question 12

formula for differing amount with blocking

Answer 12

for block size b, N per group never differes by >b/2

Question 13

blocked randomization problem

Answer 13

gives incorrect variabces and tends to bias in a cosdsrvative direction increasing power

Question 14

blockings frequecny of use

Answer 14

ALWAYS USED IN RCT OF ANY APPRECIABLE SIZE

Question 15

Randomly permuted blockes why?

Answer 15

With a constant block size you can guess the allocation of the last patient in the block and create bias.

Question 16

Solution to constant block problem of being able to anticipate the last assignment(s)

Answer 16

randomly permuted blocks. basically an additonal layer of randomization

Question 17

Should proportions of block sizes be equal?

Answer 17

No.. These are the standards for large trials they must be used in our props

Question 18

How are we able to evaulate if the randomization scheme is working?

Answer 18

It should be by design. Keep it as simple and as possilbe. Standard operating procedures that are tested and subsequently validated. Monitoring and Quality control at regular intervals.

Question 19

What is the seed

Answer 19

A randomly gnerated number to serve as a starting point in a table of randomly generated treatment assisnments

Question 20

always need to stratify by what one variable

Answer 20

Site!!

stratified randomization within the site

Question 21

do you stratify before or after randomization in RCT

Answer 21

before. it is done to ensure there are equal numbers of a group. Male and female Randomization scheme.

Question 22

overall message on stratificaiton other than site

Answer 22

we usually dont need to stratify by other factors. bc rct supposed to have balance of measured and unmeasured confounders

Question 23

for every strata you multiply by

Answer 23

each other for total number of strata.

Question 24

give number of strata

site 20 strata
gender 2 strata
other 2 strata

Answer 24

20 x 2 x2 =80 randomization schemes .

Shit gets complicated so fast man.

Question 25

problems with overstratification

Answer 25

gets complex and can empty cells.

Question 26

Standard procedure for randomization of multicenter rCTS

Answer 26

Blocked and stratified.

Question 27

blocking before or after stratificaiton

Answer 27

after

Question 28

Allcoation: why is 1:1 optimal

Answer 28

bc it is c/w equipoise of rct, and maximizes power of each enrolled pt.

Question 29

unequal alloaction may be when

Answer 29

if one rx is very cheap and one is very expensive

Question 30

4 parts to consort diagram need to include

Answer 30

1. N screened
2. N not received allocation
3. N LTF + why
4. N excluded + why (none in ITT)