Pertemuan 8
Apakah yang dimaksud dengan hipotesis?
Kenapa kita menggunakan pengujian hipotesis?
Definisi
●Hipotesis: A statement about a population parameter
●Uji hipotesis digunakan karena kita menggunakan
sampel.
Apa tahap2 pengujian hipotesis?
Tahap Pengujian Hipotesis
2
Select sig. level
3
Identify test
statistic
1
State null &
alt. hypothesis
4
Formulate
Decision
RuleDecision
Apakah hipotesis nol dan alternatif?
Bagaimana menentukan hipotesis nol dan alternatif?
Hipotesis
●Null hypothesis (hipotesis nol): hipotesis tentang
populasi
●Alternate hypothesis (hipotesis alternatif): hipotesis
yang diterima saat hipotesis nol ditolak
Cara menentukan Ho
●Yang ingin dibuktikan = hipotesis alternatif
●A company that makes processed cheese is interested in
determining whether some suppliers that provide milk for the
processing operation are adding water to their milk to increase
the amount supplied to the processing operation. It is known
that excess water reduces the freezing point of the milk. The
freezing point of natural milk is normally distributed, with a
mean of -0.545 Celsius. The cheese company is only interested
in determining whether the freezing point of the milk is less
than what would be expected from natural milk.
Cara Menentukan Ho
●whether the freezing point of the milk is less than
what would be expected from natural milk
●Rata2 susu biasa: -0.545 Celsius
●Fokus pengujian = less than natural milk = < -0.545 C.
●Ha: rata2 < -0.545 C
●H0: rata2 >= -0.545 C
Apakah yang dimaksud dengan tingkat signifikansi?
Berapa tingkat signifikansi yang digunakan di dalam
ilmu sosial?
Tingkat Signifikansi
●Adalah: kemungkinan menolak H0, padahal H0 adalah
yang benar
–α = 1-tingkat keyakinan
●5% = consumer research
●1% = quality assurance
●10% = political polling
Apa hubungan tingkat signifikansi dan type 1 error?
Apa perbedaan type 1 and type 2 error?
Type 1 and Type 2 Error
H0 diterima H0 ditolak
H0 benar Keputusan
benar
Type 1
H0 salah Type 2 Keputusan
benar
Rumus 1 Sample Test
𝑍 = 𝑋 − μ
σ 𝑛𝑍 =
𝑋 − μ
𝑠 𝑛𝑡 =
𝑋 − μ
𝑠 𝑛
Z = nilai normal standar
t = nilai distribusi t
Xbar = rata2 sampel
μ = rata2 populasi
σ = stdev populasi
s = stdev sampel
n = jumlah sampel
Kapan menggunakan Z atau t?
N >= 30?
σ diketahui?
𝑍 = 𝑋 − μ
σ 𝑛𝑍 =
𝑋 − μ
𝑠 𝑛
𝑡 = 𝑋 − μ
𝑠 𝑛
TIDAK
TIDAKYa
Ya
Kapan pakai 1 tailed dan 2 tailed test?
1 tailed atau 2 tailed?
●an economist wishes to determine whether there is
evidence that mean family income in a community
exceeds $50,000
●an economist wishes to determine whether there is
evidence that mean family income in a community
equals $50,000
Latihan
●How many tissues should the Kimberly Clark
Corporation package of Kleenex contain? Researchers
determined that 60 tissues is the mean number of
tissues used during a cold. Suppose a random sample
of 100 Kleenex users yielded the following data on the
number of tissues used during a cold: Xbar = 52, S =
22.
●Give the null and alternative hypotheses.
●Using the sample information provided, calculate the
value of the test statistic.
Latihan
●The owner of a local nightclub has recently surveyed a
random sample of n = 250 customers of the club. She
would now like to determine whether or not the mean
age of her customers is over 30. If so, she plans to alter
the entertainment to appeal to an older crowd. If not,
no entertainment changes will be made. Suppose she
found that the sample mean was 30.45 years and the
sample standard deviation was 5 years. If she wants to
be 99% confident in her decision, what decision should
she make?
Latihan
●An entrepreneur is considering the purchase of a coin-
operated laundry. The current owner claims that over
the past 5 years, the mean daily revenue was $675 with
a standard deviation of $75. A sample of 30 days
reveals a daily mean revenue of $625. If you were to
test the null hypothesis that the daily mean revenue was
$675 and decide not to reject the null hypothesis, what
can you conclude?
Rumus Proporsi
𝑍 =𝑝 − π
π 1 − π 𝑛
Z = nilai normal standar
n = jumlah sampel
p = proporsi sampel
π = proporsi populasi
Latihan
●To test this claim against the alternative that the actual
proportion of doctors who recommend aspirin is less
than 0.90, a random sample of 100 doctors results in 83
who indicate that they recommend aspirin.
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