Unit Root Test
1: What is unit root?
2: How to check unit root?
3: Types of unit root test
4: Dickey fuller
5: Augmented dickey fuller
6: Phillip perron
7: Testing Unit Root on E-views
Econometrics notes (Introduction, Simple Linear regression, Multiple linear r...Muhammad Ali
Econometrics notes for BS economics students
Muhammad Ali
Assistant Professor of Statistics
Higher Education Department, KPK, Pakistan.
Email:Mohammadale1979@gmail.com
Cell#+923459990370
Skyp: mohammadali_1979
We can define heteroscedasticity as the condition in which the variance of the error term or the residual term in a regression model varies. As you can see in the above diagram, in the case of homoscedasticity, the data points are equally scattered while in the case of heteroscedasticity, the data points are not equally scattered.
Two Conditions:
1] Known Variance
2] Unknown Variance
Brief notes on heteroscedasticity, very helpful for those who are bigners to econometrics. i thought this course to the students of BS economics, these notes include all the necessary proofs.
Definition of Co-integration .
Different Approaches of Co-integration.
Johansen and Juselius (J.J) Co-integration.
Error Correction Model (ECM).
Interpretation of ECM term.
Long – Run Co-integration Equation.
Unit Root Test
To explain the concept of Unit root test
To highlight the different names of unit root test
Explaining the, Dickey Fuller unit root test Augmented Dickey Fuller test Phillips -Perron test
Econometrics notes (Introduction, Simple Linear regression, Multiple linear r...Muhammad Ali
Econometrics notes for BS economics students
Muhammad Ali
Assistant Professor of Statistics
Higher Education Department, KPK, Pakistan.
Email:Mohammadale1979@gmail.com
Cell#+923459990370
Skyp: mohammadali_1979
We can define heteroscedasticity as the condition in which the variance of the error term or the residual term in a regression model varies. As you can see in the above diagram, in the case of homoscedasticity, the data points are equally scattered while in the case of heteroscedasticity, the data points are not equally scattered.
Two Conditions:
1] Known Variance
2] Unknown Variance
Brief notes on heteroscedasticity, very helpful for those who are bigners to econometrics. i thought this course to the students of BS economics, these notes include all the necessary proofs.
Definition of Co-integration .
Different Approaches of Co-integration.
Johansen and Juselius (J.J) Co-integration.
Error Correction Model (ECM).
Interpretation of ECM term.
Long – Run Co-integration Equation.
Unit Root Test
To explain the concept of Unit root test
To highlight the different names of unit root test
Explaining the, Dickey Fuller unit root test Augmented Dickey Fuller test Phillips -Perron test
ARDL test...Tire Lyna is the only tire casing product that has been tested and passed by ARDL, one of the most recognized labs in the world for tire/rubber testing. The test was based on OEM test standards and TMC RP.
This test is a very powerful tool and MUST be used with ever potential customer.
ARDL test,,,EXECUTIVE SUMMARY:
The purpose of this work is to determine the effect of Tire Lyna on tire durability (particularly its effect on the inner-liner and plycoat compounds). The effect was measured on roadwheel tested tires with and without Tire Lyna. The tire integrity was measured by shearography before and after roadwheel testing. The tire surface running temperatures and inflation pressures were monitored. Tire component (innerliner and plycoat) mechanical properties were measured in new and tested tire with and without Tire Lyna.
The tire tread and sidewall surface temperatures were measured as a function of roadwheel time. The tire inflation pressures were measured as a function of roadwheel time. Slightly better pressure in the tire with Tire Lyna was observed at 15 days and at the end of the roadwheel testing.
The innerliner from the tire with Tire Lyna had slightly higher tensile strength and elongation to break, and slightly lower modulus than the tire without Tire Lyna. The tire with Tire Lyna had (significantly improved) lower hardness than the tire without Tire Lyna. The improved property retention is attributed to protection against oxidation provided by Tire Lyna
Ambient temperature was measured at each tire, both tires were within ASTM ambient temperature specification. JHNB1-22-2 (without Tire Lyna) starting conditions were 100PSI /90.5T andJHNB1- 22-1(with Tire Lyna) starting conditions were 100PSI /95.2°F. Average temperature during the roadwheel test for JHNB1-22-2 (without Tire Lyna) was 99.3°F and the average temperature for JHNB1-22-1(with Tire Lyna) was 100.4°F. At the end of the roadwheel test, tire JHNB1-22-2 (without Tire Lyna) had 108PSI at 100.2°F and tire JHNB1-22-1(with Tire Lyna) had 110PSI at 98.5°F. Slightly better pressure in the tire with Tire Lyna was observed.
The test started with Tire Lyna tire being higher in temperature. During the test the tire without Tire Lyna went up to 99.3F. An increase of 8.86% and the tire with Tire Lyna went up by 5.18%. At the end of the test the tire without Tire Lyna was recorded at 100.2F. An increase of 9.68%. At the end of the test the tire with Tire Lyna was recorded at 98.5 F. A decrease in temperature by almost 2%. The tire inflation pressures are shown in Figure 9. The tire with Tire Lyna provided consistently better (higher) inflation pressure retention during and at the end of the roadwheel testing
It clearly shows and proves that the tire with Tire Lyna will run cooler and if compared to tires run in the real world without Tire Lyna the temperature difference witnessed has been as high as 20%. Tire temperatures varies on speed, elevati
A Case Study Analysis on the Asian Financial Crisis of 1997 and Zapa ChemicalsSadman Ahmed
Asian Financial Crisis of 1997:-
The Asian crisis was one of the worst financial disasters in the history of Thailand. The investors moved away large sums money away, inflation spiraled out of control, and it ultimately put pressure on the exchange rates of the Baht. Due to Thailand’s problems alone, the effect of the crisis spread along different countries in Asia. The impacts prove how integrated the economies of today are. Much of the fault lies on the failed policies of the government and weak regulatory regime.
Zapa Chemicals (risk management)
The exchange rate exposure and the legal hurdles can be quite a burden when transferring funds across the borders. In the case of Zapa Chemicals, the tax filing problem did not help them to transfer funds. They didn’t know when exactly the funds would be available for receiving. The risk management of the firm is quite a hefty task for foreign companies to successfully pursue.
Data Fusion is the process of integrating multiple data sources to produce more consistent, accurate, and useful information than that provided by any individual data source. We show how this may be accomplished in the Bayesian paradigm by constructing non-exchangeable hierarchical models with submodels for each of the several data sources. In the UQ setting, where we wish to synthesize evidence from large and slow Simulation models and possibly other data sources, it can be much more efficient to construct Gaussian Process Emulators of the Simulation models, and perform Data Fusion in the Emulators rather than the Simulators. We introduce an abstract model sitting for Fusion, and illustrate several examples from a single case study: the forecasting of hazard from Pyroclastic Density Currents (PDCs) near an active volcano.
Econometric Investigation into Cryptocurrency Price Bubbles in Bitcoin and Et...Siddharth Hitkari
At this stage, it is common knowledge that cryptocurrency prices are indeed, a bubble. However, does modern-day finance have the tools to detect explosive behaviour in absence of a fundamental value?
Glad to have worked with Shane Jose to release a paper in a bid to answer the aforementioned question!
An Econometric Investigation into Cryptocurrency Price Bubbles in Bitcoin and...Shane Jose
–A time-series analysis of BTC and ETH log-prices using Augmented Dickey-Fuller tests with recursive, rolling and reverse recursive windows.
–Successfully detects explosive behaviour while simultaneously linking real-world events to these bubbles.
Categorical Data and Statistical AnalysisMichael770443
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Computational Pool-Testing with Retesting StrategyWaqas Tariq
Pool testing is a cost effective procedure for identifying defective items in a large population. It also improves the efficiency of the testing procedure when imperfect tests are employed. This study develops computational pool-testing strategy based on a proposed pool testing with re-testing strategy. Statistical moments based on this applied design have been generated. With advent of computers in 1980‘s, pool-testing with re-testing strategy under discussion is handled in the context of computational statistics. From this study, it has been established that re-testing reduces misclassifications significantly as compared to Dorfman procedure although re-testing comes with a cost i.e. increase in the number of tests. Re-testing considered improves the sensitivity and specificity of the testing scheme.
A time series is a progression of information focuses listed in time request. Normally, a time series is a grouping taken at progressive similarly dispersed focuses in time. In this way, it is a succession of discrete-time information
06-04-2024 - NYC Tech Week - Discussion on Vector Databases, Unstructured Data and AI
Round table discussion of vector databases, unstructured data, ai, big data, real-time, robots and Milvus.
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Levelwise PageRank with Loop-Based Dead End Handling Strategy : SHORT REPORT ...Subhajit Sahu
Abstract — Levelwise PageRank is an alternative method of PageRank computation which decomposes the input graph into a directed acyclic block-graph of strongly connected components, and processes them in topological order, one level at a time. This enables calculation for ranks in a distributed fashion without per-iteration communication, unlike the standard method where all vertices are processed in each iteration. It however comes with a precondition of the absence of dead ends in the input graph. Here, the native non-distributed performance of Levelwise PageRank was compared against Monolithic PageRank on a CPU as well as a GPU. To ensure a fair comparison, Monolithic PageRank was also performed on a graph where vertices were split by components. Results indicate that Levelwise PageRank is about as fast as Monolithic PageRank on the CPU, but quite a bit slower on the GPU. Slowdown on the GPU is likely caused by a large submission of small workloads, and expected to be non-issue when the computation is performed on massive graphs.
Explore our comprehensive data analysis project presentation on predicting product ad campaign performance. Learn how data-driven insights can optimize your marketing strategies and enhance campaign effectiveness. Perfect for professionals and students looking to understand the power of data analysis in advertising. for more details visit: https://bostoninstituteofanalytics.org/data-science-and-artificial-intelligence/
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Graph algorithms, like PageRank Compressed Sparse Row (CSR) is an adjacency-list based graph representation that is
Multiply with different modes (map)
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2. Comparing various launch configs for CUDA based vector multiply.
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3. Comparing various launch configs for CUDA based vector element sum (memcpy).
4. Comparing various launch configs for CUDA based vector element sum (in-place).
Sum with in-place strategies of CUDA mode (reduce)
1. Comparing various launch configs for CUDA based vector element sum (in-place).
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Reliability Analysis (Cronbach Alpha)
Common Method Bias (Harman Single Factor Test)
Frequency Analysis (Demographic)
Descriptive Analysis
4. Contents
1: What is unit root?
2: How to check unit root?
3: Types of unit root test
4: Dickey fuller
5: Augmented dickey fuller
6: Phillip perron
7: Testing Unit Root on E-views
5. Unit Root Test
What is unit root?
A unit root test is a statistical test for the proposition that in
a autoregressive statistical model of a time series, the
autoregressive parameter is one. A unit root is an attribute of
a statistical model of a time series whose autoregressive
parameter is one. It is as:
yt=ρyt-1+ut
where -1≤ρ≤1
If ρ is in fact 1, we face what is known as the unit root
problem that is a situation of non stationary .
6. How to check Unit Root?
We start with Yt = ρYt−1 +ut
−1≤ ρ ≤1
where ut is a white noise error term. We know that if ρ
=1, that is the case of the unit root, which we know is a
non-stationary stochastic process. Then we simply
regress Yt on its lagged value Yt−1 and find out if the
estimated ρ is statistically equal to 1? If it is, then Yt is
nonstationary. This is the general idea behind the unit
root test of stationarity.
7. Steps to check unit root test
Step 1: Subtract Yt−1 from both sides of equation.to obtain
Yt −Yt−1 = ρYt−1 −Yt−1 +ut
Yt= (ρ −1) Yt−1 +ut where δ =(ρ −1)
Step 2: Now we test the (null) hypothesis that δ =0. If δ =0,
then ρ =1, that is we have a unit root, meaning the time
series under consideration is nonstationary. It may be noted
that if δ =0 then
Yt =(Yt −Yt−1)=ut
Since ut is a white noise error term, it is stationary, which
means that the first differences of a random walk time series
are stationary.
8. Types of Unit Root Test
There are three types of Unit root test
1: Dickey fuller
2: Augmented Dickey Fuller
3: Phillip perron
9. Dickey fuller test
Dickey and Fuller ( 1979, 1981) devised a procedure to formally test for
non-stationarity. The key insight of their test is that testing for non-stationarity
is equivalent to testing for the existence of a unit root. Thus the obvious test is
the following which is based on the simple AR(1) model of the form:
Yt = ρYt−1 + ut
What we need to examine here is whether ρ is equal to 1 ('unit root').
Ho: ρ = 1 (null hypothesis )
H1: ρ < 1 (Alternative hypothesis )
By subtracting both sides Yt-I with
Yt −Yt−1 = ρYt−1 −Yt−1 + ut
Yt= (ρ −1) Yt−1 +ut
Yt=ФYt−1 +ut
where of course Ф = (ρ -1).
10. The Dickey-Fuller test for stationarity is then simply the normal 't' test on the
coefficient of the lagged dependent variable Yt-I. The DF-test statistic is the t
statistic for the lagged dependent variable.
If the DF statistical value is smaller in absolute terms than the critical value
then we reject the null hypothesis of a unit root and conclude that Yt is a
stationary process.
11. Augmented Dickey Fuller
As the error term is unlikely to be white noise, Dickey and Fuller
extended their test procedure suggesting an augmented version of
the test which includes extra lagged terms of the dependent
variable in order to eliminate autocorrelation.
The testing procedure for the ADF test is the same as for the
Dickey–Fuller test but it is applied to the model
Where α is a constant, β the coefficient on a time trend and ρ the
lag order of the autoregressive process. Imposing the constraints
and corresponds to modelling a random walk and using the
constraint corresponds to modelling.
12. Phillip perron
Phillips and Perron ( 1988) developed a generalization of the
ADF test procedure that allows for fairly mild assumptions
concerning the distribution of errors. The test regression for
the Phillips-Perron (PP) test is the AR(l) process:
Yt= αₒ+ФYt−1 +ut
While the ADF test corrects for higher order serial
correlation by adding lagged differenced terms on the right-hand
side, the pp test makes a correction to the t statistic of
the coefficient y from the AR(1) regression to account for
the serial correlation in ut. So, the PP statistics are just
modifications of the ADF t statistics that take into account
the less restrictive nature of the error process.
13. Testing Unit root in e-views
Step 1: Open the file in EViews by clicking File/Open/Workfile
and then choosing the file name from the appropriate path.
Step 2: Let's assume that we want to examine whether the series
named GDP contains a unit root. Double click on the series
named 'gdp' to open the series window and choose View/Unit
Root Test .In the unit-root test dialog box that appears, choose
the type of test (i.e. the' Augmented Dickey-Fuller test) by
clicking on it.
Step 3: We then have specify whether we want to test for a unit
root in the level, first difference, or second difference of the
series. We first start with the level.
14. Step 4: We also have to specify which model of the three ADF
models we wish to use (i.e. whether to include a constant, a
constant and linear trend, or neither in the test regression).
Step 5: Finally, we have to specify the number of lagged
dependent variables to be included in the model in order to
correct for the presence of serial correlation . (For the PP test we
specify the lag truncation to compute the Newey- West
heteroskedasticity and autocorrelation (HAC) consistent estimate
of the spectrum at zero frequency).
Step 6: Having specified these options, click <OK>: to carry out
the test. EViews reports the test statistic together with the
estimated test regression.
Step 7: We reject the null hypothesis of a unit root against the
alternative if the ADF statistic is less than the critical value, and
we conclude that the series is stationary.
15. References
1: Applied Econometrics
(Dimitrios Asterius and stephen)
2: Basic econometrics
(Damodar N. Gujarati)
3:http://economics.about.com/od/economicsglossar
y/g/unitroottest.htm
4: http://en.wikipedia.org/wiki/Phillips%E2%80%93Perron_test.htm