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IBM assignment to about null hyphotesis
Citation preview
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Fortuna Shanadra – 34414002 Karen Christabel – 34414024
Paulivia Dewi – 34414027 Alvin Kristanto – 34414034
Alamsyah - 34414061
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1. Hypothesis Testing: One-Sample Single Mean with Population Standard
Deviation Unknown
The Medium B class batch 2014 students of International Business Management at Petra Christian University report the mean cost to pay car gasoline in one month is more than IDR 800 thousand rupiahs. Several students say this estimation is too low. To investigate, a random sample of 15 students were conducted. The sample information is reported below.
At the 0.05 significance level, is it reasonable to conclude that the mean cost to pay car gasoline is more than IDR 800 thousand rupiahs?
We will use the six-step hypothesis testing procedure. Step 1: State the null hypothesis and the alternate hypothesis. H0: μ ≤ IDR 800,000 H1: μ > IDR 800,000 Step 2: Select the level of significance. α = 0.05 Step 3: Select the test statistic.
𝑡 = �̅�− 𝜇𝑠
√𝑛
Step 4: Formulate the decision rule.
IDR 1,000,000 1,150,000 800,000
750,000 900,000 800,000
600,000 700,000 1,000,000
600,000 1,200,000 700,000
1,200,000 1,000,000 600,000
Solution
0 1.761
If t-test result < critical value (1.761),
then fail to reject H0 or accept H0.
If t-test result > critical value (1.761),
then reject H0 or accept H1.
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Y X1 X2 X3 X4
Company Year Stock Return Operating Profit Margin Market to Book Value Firm Size Debt Equity Ratio
PT. Astro Agro Lestari Tbk 2010 0.15 33.91% 5.72 15.99 17.90%
2011 -0.17 29.66% 4.20 16.14 21.10%
2012 -0.09 30.48% 3.31 16.33 32.61%
2013 0.27 20.55% 3.85 16.52 46.27%
2014 -0.03 22.63% 3.23 16.74 56.78%
PT. Sampoerna Agro Tbk 2010 0.18 28.37% 2.78 14.87 17%
2011 -0.06 23.83% 5.97 15.04 17.40%
2012 -0.18 16.29% 1.76 15.24 35.40%
2013 -0.17 9.23% 1.42 15.32 48.30%
2014 0.05 17.67% 1.33 15.51 56.30%
PT. Sinar Mas Agro Resources and Technology Tbk 2010 0.96 8.23% 2.46 16.34 114.00%
2011 0.28 7.80% 2.51 16.50 100.69%
2012 0.02 11.85% 2.10 16.60 81.75%
2013 0.20 8.14% 3.48 16.73 183.44%
2014 0.03 6.59% 2.93 16.87 167.97%
PT. PP London Sumatra Indonesia Tbk 2010 0.54 38.96% 19.25 15.53 22.12%
2011 -0.82 42.76% 2.63 15.73 16.31%
2012 0.02 31.44% 2.50 15.84 20.26%
2013 -0.16 24.81% 1.99 15.89 20.58%
2014 -0.02 26.25% 1.79 15.97 19.90%
PT. Gozco Plantations 2010 0.00 35.38% 4.3 14.56 73.94%
2011 0.00 33.91% 2.55 14.86 88.96%
2012 0.02 23.94% 2 14.97 99.20%
2013 -0.07 -21.53% 1.1 14.98 112.94%
2014 0.00 11.39% 1.35 14.99 107.57%
PT. Salim Ivomas Pratama Tbk 2010 0.00 23.60% 0.00 16.86 116.0%
2011 0.00 24.90% 1.20 17.05 68.0%
2012 0.00 17.70% 1.13 17.10 65.0%
2013 -0.32 13.30% 0.75 17.15 74.0%
2014 -0.10 16.30% 0.65 17.25 84.0%
Step 5: Make a decision.
𝑡 = �̅�− 𝜇𝑠
√𝑛= 𝐼𝐷𝑅 866,666.667−𝐼𝐷𝑅 800,000
𝐼𝐷𝑅 215,196.477√15
= 1.199
Step 6: Interpret the result. It is reasonable to conclude that the mean cost to pay car gasoline is more than IDR 800 thousand rupiahs.
2. Multiple Regression Analysis: Agriculture Industry
0 1.761
1.1199
The t-test result (1.199) < critical value (1.761), then fail to reject H0 or accept H0.
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SUMMARY OUTPUT
Regression Statistics
Multiple R 0.560427542
R Square 0.3140
7903
Adjusted R Square
0.204331675
Standard Error
0.255628009
Observations 30
ANOVA
df SS MS F Significance F
Regression 4 0.748034703
0.187008676
2.861836895
0.044250618
Residual 25 1.6336
4198 0.065345679
Total 29 2.381676682
Coeffici
ents Standard Error t Stat
P-value
Lower 95%
Upper 95%
Lower 95.0%
Upper 95.0%
Intercept
-0.427386686
0.974027482
-0.438782985
0.664587588
-2.433433837
1.578660465
-2.433433837
1.578660465
X Variable 1
-0.486919254
0.49725454
-0.979215301
0.336855155
-1.5110
3415 0.537195642
-1.5110
3415 0.537195642
X Variable 2
0.046019023
0.015536958
2.961906847
0.006615631
0.014020058
0.078017987
0.014020058
0.078017987
X Variable 3
0.018244903
0.061202483
0.298107231
0.768084858
-0.107803971
0.144293776
-0.107803971
0.144293776
X Variable 4
0.174482075
0.137172832
1.271987116
0.215082976
-0.108030661
0.456994812
-0.108030661
0.456994812
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Analysis 1 From the first table, we can see that R2 or coefficient of determination value is 0.314. It means that the independent variables account for 31.4% of the variation in stock return. The adjusted R2 measures the strength of the relationship between the set of independent variables and dependent variable, which is stock return, and also accounts for the number of variables in the regression equation. 0.204 means that the four variables account for 20.4% of the variance of stock return. Second, to find the regression equation, we can look into the last table. In the last table, we can see the coefficient part. Thus, If the equation is �̂� = 𝑎 + 𝑏𝑋1 + 𝑐𝑋2 +𝑑𝑋3 + 𝑒𝑋4, we can find the �̂�, and also the X1-X4. After that, we can put it on the equation and the new equation become �̂� = −0.427 − 0.487𝑏 + 0.046𝑐 +0.018𝑑 + 0.174𝑒. After we get the equation, the interpretation of this equation are:
1. An increase of 1,000 in the value of stock return is followed by the decrease in OPM for -0.487, increase in Market to Book Value for 0.046, increase in firm size 0.018, and last is an increase in debt equity ratio for 0.174.
2. Market to book value, firm size, and debt equity to ratio are positively related with stock return, while operating profit margin is inversely negative toward stock return.
Next step is that we have to conduct the global hypothesis test, in order to check if any of the regression coefficients are different from 0. We use the .05 significance level. 𝒀 = −𝟎. 𝟒𝟐𝟕 − 𝟎. 𝟒𝟖𝟕𝑿𝟏 + 𝟎. 𝟎𝟒𝟔𝑿𝟐 + 𝟎. 𝟎𝟏𝟖𝑿𝟑 + 𝟎. 𝟏𝟕𝟒𝑿𝟒 Step 1 State the null hypothesis and the alternate hypothesis Ho: 𝛽1 = 𝛽2 = 𝛽3 = 𝛽4 = 0 H1: Not all of the 𝛽s are 0 Step 2 Select the level of significance 𝛼 = 0.05 Step 3 Determine the test statistic F-test statistic
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Step 4 Formulate a decision rule
F critical value > F test reject Ho F critical value < F test failed to reject Ho Numerator = k = 4 De-numerator = n-(k+1) = 30-(4+1) = 25 F critical value with 0.05 significant level = 2.76 Step 5 Make the decision F test = 2.862 F test > F critical value Reject Ho Step 6 Interpret the result With significant level of 0.05, we can conclude that one of the regression coefficients is not equal to zero. That is why some variables must not be included in the equation. That’s we need to do a t-test to evaluate individual regression coefficient. T-Test Individual Analysis
X1 Step 1 State the null hypothesis and the alternate hypothesis Ho: 𝛽1 = 0 H1: 𝛽1 ≠ 0 Step 2 Select the level of significance 𝛼 = 0.05
2.76
Reject Ho
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Step 3 Determine the test statistic T-test statistic Step 4 Formulate a decision rule
T critical value > T test or T test < T critical value reject Ho df = 25 T critical value with 0.05 significant level = 2.060 Step 5 Make the decision T test = -0.979215301 T test < T critical value Accept Ho Step 6 Interpret the result Since the result is accepting Ho, it means that independent variable 1 is zero.
X2 Step 1 State the null hypothesis and the alternate hypothesis Ho: 𝛽2 = 0 H1: 𝛽2 ≠ 0 Step 2 Select the level of significance 𝛼 = 0.05 Step 3 Determine the test statistic T-test statistic
-2.060
Reject Ho Reject Ho
2.060
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Step 4 Formulate a decision rule
T critical value > T test or T test < T critical value reject Ho df = 25 T critical value with 0.05 significant level = 2.060 Step 5 Make the decision T test = 2.961906847
T test > T critical value Reject Ho Step 6 Interpret the result Since the result is accepting Ho, it means that independent variable 2 is not zero.
X3 Step 1 State the null hypothesis and the alternate hypothesis Ho: 𝛽3 = 0 H1: 𝛽3 ≠ 0 Step 2 Select the level of significance 𝛼 = 0.05 Step 3 Determine the test statistic T-test statistic
-2.060
Reject Ho Reject Ho
2.060
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Step 4 Formulate a decision rule
T critical value > T test or T test < T critical value reject Ho df = 25 T critical value with 0.05 significant level = 2.060 Step 5 Make the decision T test = 0.298107231 T test < T critical value Accept Ho Step 6 Interpret the result Since the result is accepting Ho, it means that independent variable 3 is zero.
X4 Step 1 State the null hypothesis and the alternate hypothesis Ho: 𝛽4 = 0 H1: 𝛽4 ≠ 0 Step 2 Select the level of significance 𝛼 = 0.05 Step 3 Determine the test statistic T-test statistic
-2.060
Reject Ho Reject Ho
2.060
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Step 4 Formulate a decision rule
T critical value > T test or T test < T critical value reject Ho df = 25 T critical value with 0.05 significant level = 2.060 Step 5 Make the decision T test = 1.271987116 T test < T critical value Accept Ho Step 6 Interpret the result Since the result is accepting Ho, it means that independent variable 4 is zero. P-value Analysis From the multiple regression table, we can see that the p-value from the calculation is 0.044. This number less than the critical value which is 0.05. We can conclude then that we reject Ho and that there is one of the coefficient which is not equal to zero. We then see the p-value for each independent variable. The p-value for X1, X3 and X4, which are the operating profit margin, the firm size and the debt to equity ratio, are bigger than the critical value. Which means that these three variable are not significant to stock return. However, p-value for X2, the market to book value, is smaller than the critical value, which means that it is significant and we need to remove the other variable which are not significant. First, we remove the first variable, which is the operating profit margin.
-2.060
Reject Ho Reject Ho
2.060
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SUMMARY OUTPUT
Regression Statistics
Multiple R 0.536442794
R Square 0.287770871
Adjusted R Square
0.205590587
Standard Error
0.255425701
Observations 30
ANOVA
df SS MS F Significance F
Regression 3 0.68537
7174 0.22
8459 3.501702077
0.029484705
Residual 26 1.69629
9508 0.06
5242
Total 29 2.38167
6682
Coeffici
ents Standard Error
t Stat P-value
Lower 95%
Upper 95%
Lower 95.0%
Upper 95.0%
Intercept
-0.503853429
0.970123744
-0.51937
0.607896036
-2.497971343
1.490264485
-2.497971343
1.490264485
X Variable 1
0.041410064
0.014795145
2.798895
0.009533965
0.010998207
0.07182192
0.010998207
0.07182192
X Variable 2
0.014434765
0.061030332
0.236518
0.814884303
-0.111014879
0.139884409
-0.111014879
0.139884409
X Variable 3
0.251335203
0.112412452
2.235831
0.034163813
0.020268099
0.482402306
0.020268099
0.482402306
We can see that there is still some p-value which is bigger than the critical value. So we remove the next variable.
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SUMMARY OUTPUT
Regression Statistics
Multiple R 0.535012583
R Square 0.286238464
Adjusted R Square
0.233367239
Standard Error
0.250920469
Observations 30
ANOVA
df SS MS F Significance F
Regression 2 0.681727474
0.340863737
5.413879932
0.010543078
Residual 27 1.699949208
0.062961082
Total 29 2.381676682
Coeffici
ents Standard Error t Stat
P-value
Lower 95%
Upper 95%
Lower 95.0%
Upper 95.0%
Intercept
-0.275768264
0.103852663
-2.655379797
0.013126633
-0.488856328
-0.0626
802
-0.488856328
-0.0626
802
X Variable 1
0.04095218
0.014409225
2.842080637
0.008430399
0.011386892
0.070517467
0.011386892
0.070517467
X Variable 2
0.257381311
0.107536511
2.393431866
0.023907791
0.036734617
0.478028006
0.036734617
0.478028006
We can see when we remove the 3rd variable, which is the firm size. There is still p-value which is bigger than the critical value. So we need to remove the last value which is not significant, the debt equity ratio.
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SUMMARY OUTPUT
Regression Statistics
Multiple R 0.367153418
R Square 0.134801632
Adjusted R Square
0.10390169
Standard Error
0.271281534
Observations 30
ANOVA
df SS MS F Significance F
Regression 1 0.321053904
0.321053904
4.362520592
0.045949814
Residual 28 2.060622779
0.073593671
Total 29 2.381676682
Coeffici
ents Standard Error t Stat
P-value
Lower 95%
Upper 95%
Lower 95.0%
Upper 95.0%
Intercept
-0.076118799
0.066884554
-1.138062446
0.264739057
-0.213125597
0.060887999
-0.213125597
0.060887999
X Variable 1
0.031214126
0.014944536
2.088664787
0.045949814
0.000601632
0.06182662
0.000601632
0.06182662
So after we left the market to book value variable only, the significant value is the same. R2 Analysis After we remove all the insignificant variable, we can see that the R2 declined significantly, while when we leave 2 variables behind, the R2 was not declining as much as when we leave 1 variable only. It means that it is okay to use 2 variables because it leads to a better result, since the R2 is closer to 1.