In general, a trend is an observable pattern in the data.

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Time series Analysis using LS

I know this is a bit of a broad question but generally if I have a time series and I want to measure whether it has trend according to time I do the following: I regress the series against time, ...
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16 views

Trend analysis for change in multivariate distribution over time

At each time point, I have a multivariate distribution $x=[x_1,x_2,x_3]$. I don't have that many time points around 3-15. I would like to know whether the change of the distribution over the time is ...
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11 views

Temporal Data set

I have a fishery data set of fourteen years in a tropical region. This kind of information is quite rare in ecological studies.The data were monthly collected and the set has 2 annual gaps and a gap ...
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58 views

Most accepted theory to analyse trend in data series

I have pollutant concentration for long period I want to determine trend. I have read some of the question answers in this blog regarding same . I have few queries. What is most accepted theory to ...
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1answer
38 views

Interpreting the result of decomposing time series

I don't have a lot of experience working with time series data. Now I have a 3 year, monthly data for several entities (you can think about them as different stores), that I would like to do some ...
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1answer
14 views

How to display potential outage when usage fluctuates greatly among customers?

I work for a Health Information Exchange. We have numerous "participants". Some send hundreds of messages a day, some might go a day or two without sending any messages. I'm creating a daily report ...
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23 views

Metric for estimating declining or ascending trend in timeseries? [closed]

I have a large number of ECG timeseries data from multiple volunteers. I calculate the signal quality in any of the given dataset by estimating the quality of the signal in a non-overlapping window of ...
3
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0answers
32 views

chi square for trend - SPSS

I have followed fourth-year university students for ten years, recording their attitudes to a particular lecture. The outcome is binary (good-bad). I have 10 rows and 2 columns, meaning year and ...
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1answer
33 views

Common trends with Difference in differences

For OLS to have good properties, we should assume that $E(u|X)=0$. When using DiD, is it then this assumption which requires the so-called common trend assumption (need for the DiD to have good ...
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1answer
23 views

Change detection in trending degradation data

I'm working with degradation data and are trying do use change detection methods to detect repairs. Since I'm looking for repairs I'm only interested in positive changes. Between the repairs the data ...
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51 views

Should outliers in a time series be removed before or after detrending?

I am doing a classical time series analysis. When do I remove outliers in the data? After detrend or before detrend?
4
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1answer
32 views

Trend Visualization of N time series

I have about 500 time series with different trends, and each time series represents a given nb of transactions. (Volumes follow a long tail distribution). I would like to plot a summary graph on ...
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29 views

Dealing with seasonality in time series with no trend

I'm working with quarterly time series data. The series does not have a trend but fluctuates around more or less a constant mean. I observe weak seasonality such that the values are somewhat lower on ...
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22 views

Does downsampling affect trend

I have a large set of time series data for which I want to identify the trend. For trend identification I am using a Simple Moving Average (SMA) function over my raw data in order to smooth them ...
2
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1answer
20 views

Approach for estimating expected time required (Regression analysis)

I am analyzing data from a factorial experiment with between subject factor Purifier (two types A and ...
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0answers
28 views

How to determine significant difference between two sets of time series data?

I have 2 sets of time series data. The data were collected from individuals who were matched (via propensity score matching) prior to collection. The only difference is that one set of matched ...
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0answers
29 views

How to find if there is a trend in a time series and stationarity

I would like to conclude on a given time series that if it has Trend or not. I have carried out a cox-stuart test in R and have decomposed to inspect the series visually but still a bit confused on if ...
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0answers
13 views

How can I identify if there is a trend?

We need an indicator/model that identify properly the market momentum of a certain array. Ideally we would like to have an indicator that swings from two given value and identify if an array is in ...
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0answers
6 views

What measures can be applied to the arrival of unique website visitors to asses whether there is an increasing or decreasing trend?

I am looking at the logs of arrivals of unique visitors to a website. I can plot the data as a histogram, and look at the plot to get an idea of whether there is an increasing or decreasing trend in ...
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1answer
56 views

How to translate percentage decline into a regression slope?

I want to model a negative relationship of count/binary data over 10 years with a known value for the decline rate (in percentage). However, I have problems in calculating the correct slope value for ...
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0answers
20 views

I am interested in conducting a trend analysis with random subject/item intercepts/slopes, in R

I have a dichotomous outcome variable and am using an IV with three levels. Is it possible to run a trend analysis in which the DV is the likelihood of success, while also including random subject ...
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1answer
50 views

Is there a rising trend in Number Series

I am trying to build a stock screening utility. What I am trying is to find if there is a rising trend in a time series of profit margins of a company. I know there can be dips in some years but I ...
2
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1answer
60 views

Statistically testing for a significant difference between two slope values [closed]

I have five trend lines plotted in excel of number of prescriptions of a 5 different drugs over time (MM/YYYY) and I want to test the statistical significance of the difference between the slopes, to ...
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0answers
39 views

Detrending or Differencing in order to make a series stationary?

I got several time series for which I want to find out if they are stationary or not. So I computed for each series the kpss.test(). But before making further ...
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1answer
49 views

The constant term after 1st differencing

My instructor stated that when the dependent variable is 1st differenced, the constant term represents the deterministic change or trend in the dependent variable. When I search for information ...
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72 views

determinstic trend in VAR-models

I'm asking myself the following question. I want to build a VAR-Model with 6 time series A, B, C, D, E and F. I analysed every series univariate and I found out that A, D, E and F are stationary and B ...
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11 views

How to adjust rank for ad for its recent trend in click-through-rate?

I am building an optimization service for an Adtech company. For ranking ads in terms of performance, I am using formula: Log(impressions)*eCPM. Impressions means the number of times ad was ...
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0answers
56 views

Seasonal Kendall test and the Mann-Kendall test

I am trying to detect trends using non-parametric methods but I'm a little confused as to when you should apply the Seasonal Kendall test. Don't get me wrong I know you apply it when you have ...
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15 views

Can you compare groups over time if data has been collected at different time points?

If have two groups with follow-up measures of a normally-distributed continues outcome measure. One group is measured at 4 time points with unequal intervals. The other group is measured at 7 time ...
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1answer
36 views

Deterministic trend and noise

I have a chicken-egg problem in time series: How do we remove the deterministic trend in time series when you have a guess that the noise is non-normal? How do we check if the noise is non-normal ...
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1answer
98 views

markov chain with probability trends

I have clients with debts that can pass from states own 1 bill, own 2 bills, own 3 bills, leave the service, new debtors and owe nothing. So I could calculate the probabilities of being in state ...
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2answers
128 views

fitting a cubic polynomial to a trend component of time series

I have 295 observations of two variables, of which here are a few: ...
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2answers
185 views

Do you see trends in my residual plots?

Do you see trends in my residual plots? These residuals plot show the standardized residuals against fitted values, origin period, calendar period, and development period. The patterns in any ...
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1answer
21 views

How do I know if this jump is going against the downwards trend?

I'm looking at some accident statistics and have a question about how it's reasonable to interpret the data. The numbers are fatalities in traffic accidents, and I want to discuss a newspaper article ...
4
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0answers
71 views

Test for trend (ordinal predictor, continuous outcome)?

I have measured a continuous outcome variable in three groups of patients, where the groups are related to the severity of disease (control, mild disease, severe disease). I would like to test for a ...
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35 views

What is the ‘Pile-up Problem’?

In methods of trend-cycle decomposition, what is meant by the 'pile up problem'? How can the pile up problem be detected? Can it be detected by the method of visual inspection? If so, what are the ...
3
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58 views

Time Series Stationarity

I am confused of why my Dickey-Fuller test is significant (which implies stationarity), while the time series clearly exhibits a deterministic trend?
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33 views

Is smooth.spline appropriate for presenting the trend of chemical concentration in a catchment [closed]

In my case,the Electrical Conductivity (EC) values are measured daily in some pints of catchment from 2007 to 2014, and around 20% data are missed, due to without probe or flux. To presenting the ...
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1answer
37 views

I am wondering what model to use [closed]

I am trying to do an analysis of popularity growth, in particular of the rate of growth in play count for artists on an online music streaming service. I want to create a postgresql db filled with ...
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0answers
25 views

Unit Root Confirmed- How generate the new series with Diff, Trend,Intercept

I have a data series that became stationary at first difference and including both Trend and Intercept. I know how to generate a new variable using first differencing (Eviews) but how should I cater ...
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18 views

Trend Survey Statistical Tests

I am designing a trend survey using a Likert style survey. I have three opinion questions, each with the same choice of responses ranging from Not Likely to Very Likely. Are there any statistical ...
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0answers
92 views

Single group with repeated measures using R? - Trend analysis (linear, quadratic effect)

I wonder how to get the repeated measures analysis of variance using R. My data is like this. ...
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0answers
8 views

Find Points that Break a mutli-valued Relationship

I am looking for a suggestion on how to answer a question, or what to read more about. I am sorry if I do not sound professional, I am not. First a contrived example. I have a table of 50 states in ...
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31 views

Infer significance (in trends) in time-series data

I got a dataset with multiple time variables (i.e. 21 fixed measurement times). It is expected that a (downward) trend over time can be discerned in these variables. When plotting scatterplots I find ...
2
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0answers
85 views

Detecting a trend to increase, in a time series, in real time

Probably, someone who's into technical analysis of share prices eats stuff like this for breakfast. Me, I couldn't devise a theoretically acceptable approach. I have this thing (private working set, ...
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2answers
41 views

Predict Seasonal Variations

I am developing an application related to pharmaceutical industry. Certain items are sold in significantly higher quantities during specific periods of the year. For example, here in my country, ...
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1answer
58 views

Can you identify what the sharp spikes in our data could be?

Scenario: There was an online competition to win a prize. The competitors are technology start-up companies and the prize is worth around 5,000 USD. There was a public, online vote to decide the ...
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0answers
105 views

STL-decomposition of a time series with deterministic trend and seasonality

what is the relationship between STL-decomposition and deterministic components of time series like trend or seasonality? I have a time series with deterministic trend and deterministic seasonality, ...
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1answer
170 views

What if the trend is changed?

I want to forecast tourist arrivals using time series analysis. I expected to use monthly data from 2000-2013. But due to the civil war, the trend was changed after 2008 as in the following plot. ...
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5answers
295 views

How to characterize abrupt change?

This question may be too basic. For a temporal trend of a data, I would like to find out the point where "abrupt" change happens. For example, in the first figure shown below, I would like to find out ...