Hypothesis Testingm5. Hyphothesis Testing

8/13/2019 Hypothesis Testingm5. Hyphothesis Testing

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HYPOTHESIS TESTING

Dr. Jamil Ahmad


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HYPOTHESIS


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In many cases the purpose of research is to answer a questionor test a prediction, generally stated in the form ofhypotheses-- testable propositions.

Examples:

QuestionHypothesis

Does a training program in driver

safety result in a decline in accidentrate?

People who take a driver safety course

will have a lower accident rate thanthose who do not take the course.

Who is better in math, men orwomen?

Men are better in math than women.

What is the relationship between age

and cell phone use?

Cell phone use is higher for younger

adults than for older adults.Is there a relationship betweeneducation and income?

Income increases with years ofeducation.

Can public education reduce theoccurrence of AIDS?

The number of AIDS cases is inverselyrelated to the amount of public

education about the disease.


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A hypothesis is an educated guess about how things work.

Most of the time a hypothesis is written like this:

"If ____[I do this] _____, then _____[this]_____ will happen."

(Fill in the blanks with the appropriate information from your own

experiment.)

What is a Hypo thesis?

A hypothesis is a statement about the relationship between two or more

variables. A hypothesis requires at least two variables, one independent

variable and one dependent variable.

Your hypothesis should be something that you can actually test, what's

called a testablehypothesis. In other words, you need to be able to

measure both "what you do" and "what will happen."

What is a Hypo thesis?


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A hypothesis is an explanation for a phenomenon which can

be tested in some way which ideally either proves or

disproves the hypothesis.

A statement about some population parameter that is to be

tested for its correctness.

A tentative explanation for an observation, phenomenon, or

scientific problem that can be tested by further investigation.

Hypothesis is a formal statement that presents the expected

relationship between an independent and dependentvariable.(Creswell, 1994)

A research question is essentially a hypothesis asked in the

form of a question.

What is a Hypothesis?


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It can be tested

Hypotheses are not moral or ethical questions

It is a prediction of consequences

It is considered valuable even if proven false

Natureof Hypothesis


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NULL HYPOTHESES

Designated by: Ho

Pronounced as H oh or H-null

(hipotesis nol, hipotesis kosong, hipotesis tidak beza)

Ho: 1 = 2

Ho: 1 - 2 = 0

ALTERNATIVE HYPOTHESES

Designated by: H1 or Ha

Ha: 1 2

Types of Hypotheses


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The alternative hypothesis is a statement of what ahypothesis test is set up to establish.

Opposite of Null Hypothesis.

Only reached if Ho is rejected.

Frequently alternative is actual desired

conclusion of the researcher!

ALTERNATIVE HYPOTHESIS


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Contoh:

Dalam satu kajian bagi mengenal pasti keberkesanan kaedah pengajaran

berbantukan komputer berbanding dengan kaedah tradisional dalam

meningkatkan pencapaian pelajar dalam mata pelajaran sains.

Soalan kajian:

Adakah terdapat perbezaan pencapaian pelajar dalam mata pelajaran sains

antara kumpulan yang diajar dengan kaedah pengajaran berbantukan

komputer berbanding dengan kaedah tradisional?

Hipotesis nol:Ho: Tidak terdapat perbezaan yang signifikan skor min pencapaian pelajar

dalam mata pelajaran sains antara kumpulan pelajar yang diajar dengan

kaedah berbantukan komputer berbanding dengan kumpulan tradisional.

Ho: 1 = 2

Hipotesis alternatif:

Ha: Terdapat perbezaan yang signifikan skor min pencapaian pelajar dalam

mata pelajaran sains antara kumpulan pelajar yang diajar dengan kaedah

berbantukan komputer berbanding dengan kumpulan tradisional.

Ha: 1 2 (two-Tailed/sided)


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CONTOH SOALAN KAJIAN

1.

Adakah terdapat perbezaan tahap budaya penyelidikan antaraguru sekolah bandar dengan guru sekolah luar bandar?

Hipotesis nol:

Ho. Tidak terdapat perbezaan yang signifikan tahap budayapenyelidikan antara guru sekolah bandar dengan guru sekolah

luar bandar.

Hipotesis alternative:

Ha: . Terdapat perbezaan yang signifikan tahap budaya penyelidikan

antara guru sekolah bandar dengan guru sekolah luar bandar.


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Thepvalue is the probability that the samples are from the same

population with regard to the dependent variable(outcome).

Usually, the hypothesis we are testing is that the samples (groups)

differ on the outcome.

Thepvalue is directly related to the null hypothesis.

Thepvalue determines whether or not we reject the null hypothesis.

We use it to estimate whether or not we think the null hypothesis istrue.

LEVEL OF SIGNIFICANCE (pvalue)


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Thepvalue provides an estimate of how often we would get theobtained result by chance, if in fact the null hypothesis were true.

If the pvalue is small, reject the null hypothesis and accept that the

samples are truly different with regard to the outcome.

Ifthe pvalue is large, accept the null hypothesis and conclude that

the treatment or the predictor variable had no effect on the outcome.

??????????

How small is "small?

Whatpvalue should we use as a cutoff?

LEVEL OF SIGNIFICANCE (pvalue)


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In the behavioral and social and sciences, a generalpattern is to use either .05 or .01 as the cutoff.

The one chosen is called the level of significance.

If the probability associated with an inferential statistic is

equal to or less than .05, (p .05) then the result is said tobesignificant at the .05 level.

If the .01 cutoff is used, then the result is significant at the

.01 level.


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Using the .05 level of significance means if the null hypothesis is true,

we would get our result 5 times out of 100 (or 1 out of 20). We take the

risk that our study is notone of those 5 out of 100.

Rejecting or accepting the null hypothesis is a gamble.

There is always a possibility that we are making a mistake in rejecting

the null hypothesis.

This is called a Type I Error - rejecting the null hypothesis when it is

true.

If we use a .01 cutoff, the chance of a Type I Error is 1 out of 100.

With a .05 level of significance, we are taking a bigger gamble. There is

a 1/20 (5 out of 100) chance that we are wrong, and that our treatment

(or predictor variable) doesn't really matter.


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The Decision Criterion


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Alpha Level


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Critical Region

A very small


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The locations of the critical region boundaries for three different

levels of significance: = .05, = .01, and = .001.

2.5% on

either side

.5% on either

side

A very small

number on either

side


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Types of error

Type of decision H0true H0false

Reject H0 Type I error () Correct decision (1-b)

Accept H0 Correct decision (1-) Type II error (b)

If you reject Ho when it is false, youve made a correct decision (upper-

right cell)

However, if you reject Ho when it is true, youve made a Type I error

(upper left cell)

This error has a particular name, alpha.

On the other hand, if Ho is false and you do not reject Ho, you commit

a Type II error .

The probability of committing a Type II error is called beta.


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CONCEPT DESCRIPTION

Null Hypothesis The hypothesis stating that the independent variables has no

effect and that there will be no difference between two groupsAlternative

Hypothesis or

Research

Hypothesis

The hypothesis stating that the independent variables has an

effect and that there will be a difference between two groups

Two-Tailed orNondirectional

Test

An alternative hypothesis stating that a difference is expectedbetween the two groups, but there is no prediction as to which

group will perform better or worse

One-Tailed or

Directional Test

An alternative hypothesis stating that a difference is expected

between the two groups, and it is expected to occur in a

spesific direction.

Type I Error The error of failing to reject Ho when we should have reject it

Type II Error The error of rejected Ho when we should have failed to reject it

Statistical

Significance

When the probability of a type I error is low (less than .05)

SUMMARY


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TERIMA KASIH

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