Experimental design

Variables

• Independent variable

• Dependent variable

• Levels

• Responses

Example 1

Subjects are given two types of constructions and are asked to decide whether the given sentence is grammatical:

(1) a. I gave him it. Construction 1b. I gave her the book.c. …

(2) a. I gave to him it. Construction 2b. I gave to her the note you sent me.c. …

Example 1

IV (two conditions) DV (forced choice task)

Construction 1Construction 2

a. grammaticalb. ungrammatical

Example 2

Subjects are asked to complete copular sentences with a relative clause. The predicate nominals of the copular clauses belong to three different semantic types: (1) animate/human (2) inanimate/object (3) place.

(1) a. This is the man __ b. This is the ball __c. This is the place __

Example 2

IV DV

1. This is the man __ 2. This is the ball __3. This is the place __

a. SUBJ relative clauseb. DO relative clausec. IO relative claused. OBL relative clausee. GEN relative clause

Example 2

IV DV

1. This is the man __ 2. This is the thing __3. This is the place __

a. SUBJ relative clauseb. DO relative clausec. IO relative claused. OBL relative clausee. GEN relative clause1. I saw the man __

2. I saw the thing __3. I saw the place __

Example 2

Condition 1 Condition 2

SUBJ 3.5DO 3.2IO 2.7OBL 2.2GEN 0.6

SUBJ 2.5DO 3.8IO 3.2OBL 0.5GEN 0.5

Types of data

• Nominal/categorical data

• Ordinal data

• Interval data

Type of analysis

• Correlational analysis

• Difference test

Type of analysis

Correlational test Difference test

Pearson‘s rKendall‘s tau

T-testANOVA

Confound variables

(1) … the man who talked to Mary.(2) … the car that caused the accident.(3) … the man who Mary talked to.(4) … the car that Peter bought.

Confound variables

(1) … the man who talked to Mary.(2) … the car that caused the accident.(3) … the man who Mary talked to.(4) … the car that Peter bought.

Confound variables

• Control

• Randomization

Sampling

• Simple random sampling• Stratified random sampling• Systematic sampling• Cluster sampling

Related and independent design

• Within subjects design – related design – repeated measures design

• Between subjects design – unrelated design – independent design

Advantages of within subjects design

• Reduction of inter-individual differences

• Fewer subjects

Disdvantages of within subjects design

• Subjects recognize the purpose of the study.

• Subjects get tired, frustrated, excited.• Subjects get habituated to the task.

Responses to IVs/conditions can influence each other:

Counterbalancing

• ABBA• AB - BA

Counterbalancing serves to eliminate the ordering effect.

Counterbalancing

1.ABC 2.ACB3.BAC4.CAB5.BCA6.CBA

Experimental design

A child language researcher wants to find out if the meaning of the head of a relative clause influences the interpretation of the acquisition of relative clauses in early child speech. Specifically, he wants to know if animate and inanimate head nouns affect children’s interpretation of relative clauses. In this study, he concentrats on the two most frequent types of relative clauses in which the subject and object are relativized (i.e. expressed by the relative pronoun).

Experimental design

(1) Das ist der Mann, der das Mädchen gestern gesehen hat.

(2) Das ist der Mann, den das Mädchen gestern gesehen hat.

(3) Das ist der Ball, der das Mädchen am Kopf getroffen hat.

(4) Das ist der Ball, den das Mädchen mit dem Kopf getroffen hat.

Experimental design

(1) Das ist der Mann, der das Mädchen gestern gesehen hat.

(2) Das ist der Mann, den das Mädchen gestern gesehen hat.

(3) Das ist der Ball, der das Mädchen am Kopf getroffen hat.

(4) Das ist der Ball, den das Mädchen mit dem Kopf getroffen hat.

Experimental design

Animate head Inanimate head

Subject

Object