Questions tagged [test-for-trend]

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1answer
1k views

Decompose a time series data into deterministic trend and stochastic trend

Given the comments below, I reformed my questions with more background information and simulation/examples. My question also includes the validity of the method in theory. Please correct me if any ...
4
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1answer
5k views

Interpretation of Mann-Kendall statistics

I am doing a trend analysis for vegetation dynamics using Mann-Kendall test for trend detection and Sen's slope for computing the magnitude of the trend. There are 6 sites inside a conservation area ...
4
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0answers
43 views

Simple trend analysis with unbalanced & short panel data

I have the following (unbalanced) panel data: yearly sustainability ratings (ESG) of ca. 2000 individual firms over a 11-year period. The average observations per firm only covers 5.3 periods. These ...
3
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2answers
307 views

Why ARIMA/ARMA is performing very bad on out of sample (future) prediction?

I am working on a time series forecasting problem. The time series is - I plotted the rolling mean and rolling variance - rolling mean - and the rolling variance- The rolling mean/variance has not ...
3
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2answers
734 views

What is the best way to proof your time series has a deterministic linear trend

In case you suspect your time series has a linear trend, what is the best way to prove it? If you just regress it against time, you ignore the auto correlation of the time series so I assume that is a ...
3
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1answer
1k views

Detect unusual trends and anomalies using mixed data (categorical and numerical)

I've been asked to detect "unusual trends and anomalies" using data similar to ATM transaction data. Each entry has a mixture of numerical and categorical variables, things like transaction ID, ...
3
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1answer
43 views

Is there a method to disentangle multiple lines of data that are intermingled?

I have 3 temperature sensors that record data once a minute. All 3 temperatures have the tuple value (instant, temperature). The problem is, they may come in a random order and thus there's no way to ...
2
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1answer
1k views

Detrending or not and should I always take log first?

I have some trouble with a specific time series. The time series itself is pretty short: Only 73 observations that look like this: First problem: Detrend or not? First I need to find out if the time ...
2
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1answer
773 views

Change in proportion in two populations over time

I have a data set composed of two groups which had two different treatments. They are treated over 8 weeks. The endpoint is binary - either they respond or not during each week. Thus, for any given ...
2
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1answer
1k views

Would including “year” as a categorical random effect remove a long-term trend in a mixed effects model?

I am trying to detect evidence of warming in a monthly temperature time series over a 20-year period by testing for a trend. I have precisely followed the method of Crawley (2013) The R Book, 2nd ...
2
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2answers
2k views

Mann-Kendall test in R using 'Kendall' package: exact test or approximation?

Problem: I am trying to perform a test for trend using the MannKendall() function available in the Kendall R package. My number of data points is n=11. For this ...
2
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0answers
19 views

p trend for Hazard Ratios of a categorical independent variable

I ran an analysis using a Proportional Hazards Cox regression model. My variable of interest is exposure to pesticides (kg of pesticides applied within 500m of home). We do not expect a linear ...
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0answers
96 views

Looking at trend in count data

I have a clinic dataset with count data collected on a monthly basis from January 2013 - May 2018. There are 20+ variables. Almost all of them are "number of patients who accepted xyz treatment" in [...
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0answers
52 views

Nonparametric test for difference in trends?

I have an experiment where two groups of individuals get some variable repeatedly measured at regular intervals. I'd like to know if one group is trending faster or slower than the other (and in what ...
2
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1answer
82 views

unit root tests: trend included for bounded series

X lies in a 0,100 interval and i want to check if X has a unit root. In (A)DF, and PP unit root tests one can have an intercept and/or a trend (in addition to the level and difference X lags). But ...
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0answers
304 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 ...
2
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0answers
3k views

How to perform a test for trend on an ordinal variable in logistic regression?

I have a dichotomous outcome (gallstones/no gallstones) and an ordinal predictor variable consisting of four classes (body mass index <25(ref.), 25-30, 30-35, 35-45). I want to perform a test for ...
2
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0answers
758 views

Equivalence of p-values from Jonckheere-Terpstra test and Kendall's tau

I'm using the Jonckheere-Terpstra test to confirm whether an interval variable, distributed across five levels of an ordinal variable, display a significant trend. I'm using the clinfun package, ...
2
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0answers
546 views

What is a “Wald test for trend?”

I am reviewing a manuscript and the authors state that some results are by a "Wald test for trend". Has anyone heard of this? I hadn't, and Google revealed nothing. I know I always say to provide ...
2
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0answers
34 views

what test for analysing level of agreement of users perception on species population trends from ordinal categorical data

This is my first post ever so I beg you please forgive me any mistake (I'm also super newbie in stats). I have this dataset that comes from interviews filled by users (divers) about their perception ...
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3answers
4k views

Trend Analysis: How to tell random fluctuations from actual changes in trends?

I hope somebody in here can help me: I'm looking for some pointers as to how to distinguish random fluctuation from actual changes in trends, e.g.: In a time series with measures taken at monthly (...
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2answers
37 views

Choosing trend analysis period

I'm having trouble figuring out whether its important to have a common period of time when performing hypothesis testing for trend analysis. I have time-series data of varied length - some sites have ...
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1answer
129 views

Linear Regression Approach For Trends

I'm working on a project with genetics but I think my problem is applicable to general statistics. I want to test frequency (Minor Allele Frequency) of a SNP/variant across 5 age categories to see ...
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2answers
95 views

Detrending a nice series with dummys and a break

I have a problem with a time series. In short: How do I detrend a time series with a break and some big outliers? Long version: I want to detrend a time series into a trend and some cyclical ...
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1answer
549 views

Huge discrepancy between analytic Mann-Kendall statistic and its block bootstrap estimate

I am analyzing some environmental time series and I use Mann-Kendall test to check for monotonic trends. However, I am a little bit concerned about autocorrelations in my data, since standard Mann-...
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1answer
429 views

Are my data values too small for chi-squared for trend? If so what trend test can I do instead?

I'm doing a project about dilated kidneys, these can be arranged into mild, moderate and severe. There are 53 patients in total. I want to see if there is a trend in the severity of dilatation between ...
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2answers
57 views

Trend & Seasonality Determination in Time Series without looking at Graph [duplicate]

Most of the articles I have read describe determining Trends and Seasonal (TS) effects through rolling your eyes on Graphs. Graph is a nice visual representation, but I am looking a way in either ...
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1answer
624 views

What if Cochran-Armitage test (“linear by linear association” for trend in SPSS) is significant but associated chi-square test is not signficant?

I administered a customer service satisfaction survey, and one of the questions is a check-all-that-apply asking respondents to check the boxes for the services that they liked most (medication ...
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1answer
2k views

Mann-Kendall's trend test result

I'm running the Mann-Kendall trend test on my data (35 different vectors, 5 elements each). What I'm doing for each one is: ...
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1answer
101 views

How do I test for trend in sum of random variable?

I have a dataset with cost measurements for hospital admissions of ~25,000 patients over multiple years. Cost seems to be log-normal distributed and taking the logarithm results in an approximately ...
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1answer
243 views

Trend prediction with binary data

I have data of 11 years where for each year the values are binary (0 and 1). The sample sizes for each year are different (for example for 1989 n=8 and for 2004 n=30). The goal is to see if there is a ...
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0answers
16 views

Test for trend across ordinal categories: which test to use?

I want to test for a trend in a continuous (non-normal) response variable across ordinal categories. I came across multiple test that seem suitable for this problem. Particularly, the R package ...
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0answers
8 views

Modeling and testing for trends in hospital-surveillance (count, event) data

Intro Hi all, I'm working with hospital-based surveillance data. My peers and I are trained (loosely speaking) as frequentists. I'm mindful of the aphorism: Statistics: A subject which most ...
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0answers
123 views

Seasonal Mann Kendall vs Mann Kendall test [closed]

Does anyone have any thoughts on the use of these methods and when both might be used to explore trends in the data. I think most people who sample monthly, quarterly or biannually would jump ...
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1answer
28 views

how should I specify a deterministic trend in my time series data?

How can I specify a trend (term) in my time series data? does it have a logical procedure or is it totally base on visual interpretation of historical plot?
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0answers
42 views

What is the statistical test to use for a trend analysis for continuous variables (non-paired)?

Please excuse my very elementary question... Please see attached graph. This is an example of the kind of data I'm trying to analyze. The data points are non-paired. There is definitely a time-...
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0answers
59 views

Ordered Chi squared or trend tests

I've applied the Stata non-parametric test for trend (nptrend) for a two-way table including one ordered categorical data (quintiles of deprivation index). Such clearly ordered variables are ...
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1answer
393 views

Significance of a trend [closed]

How would I work out if my data (sea ice extent) has a statistically significant trend (increase/decrease)? It is one value per year from 1979 to 2017.
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0answers
15 views

A test for Explantory method for testing if multiple pooled cross-sectional panels have same trend

I am trying to test to see if there is a "universal" trend in homicide across multiple nations. First, I utilized squared semi-partial correlation coefficient by estimating two models (1) a model ...
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0answers
119 views

Implementing Hamed and Rao (1998) and Yue and Wang (2004) Modified Mann-Kendall test in R- Help with Correction Factor Calculation?

I am trying to modify the code mkTrend.R from 'fume' package to implement Hamed and Rao (1998) variance correction approach. From the code of mkTrend, the following line is very confusing (Line-29 to ...
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0answers
92 views

Can the Mann Kendall Trend test be used on binary data?

If I have a dataset consisting of binary data e.g. (0,1,0,1,1,0,1,1,1,0,0,1), can I use the Mann-Kendall test to determine if there are an increasing or decreasing number of 1's? (My question is less ...
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0answers
14 views

Nonlinear methods for detecting and measuring the strength of a trend in the context of unit roots

I am looking for statistical methods to detect the presence and strength of a trend in the context of unit root testing. We could for instance use a trend-stationarity ADF test: Here the t-statistic ...
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0answers
171 views

Stochastic or deterministic trend

Having run panel unit root tests, we cannot reject the null of individual unit root (Im, Pesaran), suggesting a non-stationary series. Question 1 At this point, how do we know if we have a ...
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0answers
116 views

Using the likelihood-ratio test as a Cochran-Armitage test for trend

Maybe this is a silly question, but I need to perform a test for trend in a 2x3 contingency table and I've been said to use the Cochran-Armitage test for trend with weights (0, 1, 2). Okay, that's ...
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1answer
151 views

Doubts on ARIMA models forecast to account for an exponential trend only later in time

I have a 10 years daily data series, with no indicative trend on the first 8 years but seemingly exponential growth in the last 2. I’m using R with forecast ...
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0answers
17 views

Which test to determine if there is a difference between pharmacological reaction and population characteristic (e.g. ethnicity) in R?

I have a data set where each row represents an individual and their respective measure of pharmacological reaction (protein level) in addition to their epidemiologic characteristics (e.g. ethnicity, ...
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0answers
2k views

Is there an accepted definition for “P for trend” or “P-trend” [duplicate]

So is "P for trend" the same in principle as a common-or-garden P-value, but in a specific application i.e. odds ratios? And can P-value, P for trend, and P-trend be regarded as interchangeable ...
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1answer
783 views

How to determine trend in rainfall data?

I have annual average rainfall data in mm/day units. I want to see the trend of the rainfall, whether its increasing or decreasing. How to do this. My teacher told to put a linear regression line and ...
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0answers
955 views

How to deal with different numbers of days in a month for comparison?

My question is very basic, and I'm looking for a conceptual answer. We put about 55000 values (individual deliveries) on a graph. They are sorted by day of the month to see if there's a trend and to ...
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1answer
76 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 ...