Lecture 1 - Experimental Design and Analysis

Question 1

What’s another name for the IV

Answer 1

the treatment variable

Question 2

What’s another name for the DV

Answer 2

the measure

Question 3

Which is experimentally manipulated, the IV or the DV

Answer 3

the IV

The DV changes because of the changes in the IV

Question 4

What are quantitative variables

Answer 4

they respresent variation in amount such as ‘amount of drug’ ‘loudness of stimuli’ etc

Question 5

What are qualitative variables

Answer 5

they represent variation in kind or type eg classical music, rock music, teaching strategy

Question 6

What are classification variables

Answer 6

they systematically vary characteristics which are intrinsic to the subjects of the experiment, such as age, gender, species, word type, IQ etc

Question 7

What is a nuisance variable?

Answer 7

Potential IV’s that if uncontrolled may have a SYSTEMATIC influence on the different treatment conditons
such as time of day, the researcher doing it etc

Question 8

What is a randomised block design?

Answer 8

uses blocks of subjects who are matched closely on a relevent attribute

Typically a subject is treated as a ‘block’ - they serve in all the treatment conditons of the IV

So this is basically a fancy way of talking about a type of repeated measures design.

Question 9

Describe what a statistical hypothesis is

Answer 9

Statistical hypothesis are a set of precise hypothesis about the parameters of the different treatment populations

Question 10

What is a (alpha)

Answer 10

the significance level (usually 0.05)

Question 11

What is a type 1 error?

Answer 11

We wrongly accept the alternate hypothesis and reject H0 = we see an effect where thee isn’t one

We may be willing to accept more type 1 errors when we want to discover new things

Question 12

What is a type 2 error?

Answer 12

We wrongly accepy H0 and reject the H1 = we fail to see an effect even though one is there

We may be willing to accept more type 2 errors when we don’t want to falsely assume something (e.g. safety of a medicine)

Question 13

What is a research hypothesis?

Answer 13

Research hypothesis are general statements about the assumed nature of the world that is then translated into creating an experiment

Question 14

What is H0?

Answer 14

the null hypothesis (its H with the 0 below it rather than on the same line, like a chemistry symbol)

Question 15

What does u1, u2, u3 mean (u with the long line on the left hand side)

Answer 15

they represent the results of the conditions (usually the mean)

Question 16

What is H1?

Answer 16

the alternate hypothesis

Question 17

What is an important limitation of the data collected in any experiment, with respect to the hypothesis?

Answer 17

The data collected tells us about a sample but the hypothesis aims to make a prediction about the whole population - this is why we must decide whether to accept or reject h0

Question 18

How do we decide whether to accept or reject H0?

Answer 18

We calculate a test-statistic based on the f-distribution value of our data. The value we adopt is called the significance level and is referred to as a (alpha). Usually our alpha is 0.05 in psychology.