EXPERIMENTAL EXPERIMENTAL PSYCHOLOGYPSYCHOLOGY

Module 1Lesson 5

HYPOTHESIS

HypothesisHypothesis

Thesis, or main idea of an experimentIt is a statement about a predicted

relationship between at least two variables

Nonexperimental hypothesisNonexperimental hypothesis

Statement of your predictions of how events, traits or behaviors might be related- not a statement about cause and effect.

Experimental HypothesisExperimental Hypothesis

Tentative explanation of an event or behavior. It is a statement that predicts the effects of specified antecedent conditions on a measured behavior.

Characteristics of an Experimental Characteristics of an Experimental HypothesisHypothesis

Synthetic statements- those that can either be true or false◦Analytic statement- one that is always true◦Contradictory statements- statements with

elements that oppose each other

Characteristics of an Experimental Characteristics of an Experimental HypothesisHypothesis

Testable statements- the means for manipulating antecedent conditions and measuring the resulting behavior must exist

Falsifiable statements- disapprovable by research findings

Characteristics of an Experimental Characteristics of an Experimental HypothesisHypothesis

Fruitful- leads to new studiesParsimonious statements- simple

explanation

Process of Formulating Process of Formulating HypothesisHypothesis

Inductive Model

Deductive Model

Combination of Inductive and Deductive Model

Finding for a HypothesisFinding for a Hypothesis

Building on prior researchSerendipity and the windfall hypothesisIntuition“when all else fails…”

To establish whether the obtained sample difference is statistically significant- the result of a real population difference and not just sampling error- it is customary to set up a level of significance, denoted by the Greek letter (alpha).

Alpha value is the level of probability at which the null hypothesis can be rejected with confidence and the research hypothesis can be accepted with confidence. P < .05

To be statistically significant, the obtained value must exceed or be less than the critical value depending on the test used.

Levels of SignificanceLevels of Significance

DECISION Retain Null Reject Null

RE Null isA TrueLIT Null isY False

Type I and II ErrorsType I and II Errors

CORRECT DECISION

Type I Error p(Type I Error) =

Type II Error p(Type II Error)=

CORRECT DECISION

P is the exact probability that the null hypothesis is true in light of the sample data.

The alpha value is the threshold below which is considered so small that we decide to reject the null hypothesis.

Decision to reject the null hypothesis is made if the P value is less than the alpha value and otherwise retain it. NOTE: FOR A Z TEST

HOWEVER, for a t test, the computed t must be greater than or equal to the value of the alpha level set.

What is the difference between p and What is the difference between p and ??

STEPS in STEPS in HYPOTHESIS TESTINGHYPOTHESIS TESTING

SAMPLE ACTIVITY:The One-Way Analysis of Variance

(ANOVA)

Chapter 13 - 15

PROBLEM1– Sincerity Scale by Year LevelPROBLEM1– Sincerity Scale by Year LevelUsing the following data set, conduct a one-way ANOVA among students of DLSU-D, at 0.01 determine the significant difference of the independent variable. Provide the summary table. Give a post hoc (?) if significant. Apply the steps in Hypothesis Testing.

totalX 2totalX NtotalX

1st year 2nd year 3rd year 4th year

20 19 10 11

19 18 11 11

17 18 15 10

15 15 11 10

15 16 15 12

16 16 14 11

17 10 10 13

3X22X2X

21X 2

3X1X 24X4X

1191 X 21X 2

2X 23X1122 X 863 X

1X71 n 72 n 73 n2X 3X

784 X 24X

4X74 n

Chapter 13 - 16

Source Sum of df Mean FSquares Squares

BetweenWithinTotal*fcrit at α 0.05 -- ?Not Significant/ Significant**fcrit at α 0.01 -- ?Not Significant/ Significant

Compute your Compute your f-ratiof-ratio, then, provide the , then, provide the Summary Table of F-ratioSummary Table of F-ratio

Chapter 13 - 17

?)( wn

n

MSqHSD k

Post Hoc (When to use?)Post Hoc (When to use?)

?

?

?

?

?

?

43

42

32

41

31

21

XX

XX

XX

XX

XX

XX

Chapter 11 - 18

Perform the Steps in Hypothesis Testing:Step 1: Formulate your H0: and Ha:Step 2: Identify your

at 0.01 the Step 3: Compute the F-testStep 4: Decision:

Accept Ho; or Reject Ho then Accept Ha

Step 5: Conclusion: Therefore, _____

?crit f

PROBLEM1– Sincerity Scale by Year Level

ANSWERSANSWERS

Chapter 13 - 20

Source Sum of df Mean FSquares Squares

Between 168.39 3 56.13 11.79Within 114.29 24 4.76Total 282.68 27*fcrit at α 0.05 -- 3.01 Significant**fcrit at α 0.01 -- 4.72 Significant

ANSWERANSWERSummary Table of F-ratioSummary Table of F-ratio

Chapter 13 - 21

68.28228

3955855

)( 22tot2

tottot

N

XXSS

39.16828

395

7

78

7

86

7

112

7

119

)(

columntheinscoresof

)columntheinscoresofsum(

22222

2tot

2

bn

N

X

nSS

29.11439.16868.282bntotwn SSSSSS

SUMS of Squares SUMS of Squares

Chapter 13 - 22

Degrees of FreedomDegrees of Freedom

dfbn = k - 1 = 4 - 1 = 3 Numerator

dfwn = N - k = 28 - 4 = 24 Denominator

dftot = N - 1 = 28 - 1 = 27

Chapter 13 - 23

13.563

39.168

bn

bnbn

df

SSMS

76.424

29.114

wn

wnwn

df

SSMS

79.1176.4

13.56

wn

bnobt

MS

MSF

Mean of Squares and FMean of Squares and Fobtobt

Chapter 13 - 24

degrees of freedom (df= 3 and 24)

Fcrit (4.72) at 0.01.

Since Fobt = 11.79, the ANOVA is significant

SIGNIFICANCE then, use Tukey.

Chapter 13 - 25

05.47

76.491.4)( wn

n

MSqHSD k

Post HocPost Hoc

15.1

86.4

71.3

86.5

71.4

0.1

43

42

32

41

31

21

XX

XX

XX

XX

XX

XX

Chapter 11 - 26

Perform the Steps in Hypothesis Testing:Step 1: Formulate your H0: and Ha:Step 2: Identify your

dfb= 3, dfw= 24, dftot= 27 at 0.01 the

Step 3: Compute the f-ratio Step 4: Decision:

Reject Ho, then Accept HaStep 5: Conclusion:

Therefore, there is A SIGNIFICANT difference…

72.4crit f

PROBLEM1– Sincerity Scale by Year Level

79.11obt f

EXPERIMENTAL EXPERIMENTAL PSYCHOLOGYPSYCHOLOGY

QUIZ # 3QUIZ # 3

Multiple choice: Multiple choice: Write the letter of Write the letter of the correct answer. (2pts each)the correct answer. (2pts each)

1. A good experimental title for a report should _____.

a. provide summary of essential resultsb. give an idea of what the report is aboutc. state the major experimental hypothesisd. include the names of the authore. all of the above

2. Our manuscript for this subject should follow the format given by ___.

a. APA Publication Manualb. Manual of the Psychonomic societyc. Science Foundation Manuald. Style Guide for Psychological Reportse. DSM V

3. Which of the following is not a major section of the research report?

a. introduction b. method c. prologue d. results e. discussion

4. A good and standard length for an abstract in a journal would be about ___.

a. 50 to 75 words b. 100-120words c. 200-300 words d. 150-200 words

5. The purpose of the Discussion section is to ____.

a. explain non-significant findingsb. evaluate and interpret the resultsc. summarize the studyd. justify continued experimentatione. review all prior research in the area

B. Indicate what section of the manuscript B. Indicate what section of the manuscript where the following could be found. where the following could be found. (2 pts each)(2 pts each)

1. A tentative assumption of the study.2. F(1,2) = 6.26, p< .013. summary of the study4. review of related literature5. table of data and figures6. Includes subsections such as participants,

apparatus and procedure7. list of books used for the review of related

literature8. generalization and conclusions of the study.9. narrative description of data10. recommendations of the study.

C. APPLICATION (2 pts. Each)C. APPLICATION (2 pts. Each)A researcher reported that A researcher reported that t (?) 6.875, t (?) 6.875, αα = .05; n=49; = .05; n=49; with tabulated value of with tabulated value of 3.143.14.. (Decisiveness and Mental Ability)(Decisiveness and Mental Ability)

1. Was the null hypothesis rejected?2. How many percent are you confident

that the obtained value did not occur by chance alone?

3. What was the degree of freedom?4. Was there significant difference between

the groups being compared? Explain Why.

ANSWERSANSWERS

1. B2. A/D3. C4. B5. B

1. Hypothesis (Introduction)

2. Result3. Abstract or Discussion4. Introduction5. Result6. Methods7. References8. Discussion9. Method10. Discussion

1. Yes…Ho: There is no significant difference on the level of decisiveness among participants with varying mental ability.

2. 95 % of confidence3. df=48 (n-1)4. Yes, since the tobt (6.875) is > tcrit (3.14)

at α = .05. This implies that there is a significant difference between the two groups being studied.