Questions tagged [test-for-trend]

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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 ...
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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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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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1answer
1k views

Back-transforming contrast lstrends results in r

I calculated a linear mixed model using the packages lme4 and lsmeans with the lmer-function, where i have one dependent variable rv and the interacting factors treatment, time, age and race. I'm ...
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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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2answers
523 views

Is there a nonparametric test available in R to test for a trend in a binary variable?

I have e.g. the following (n=14) time series data: 0,0,0,1,0,1,0,1,1,0,1,1,1,0 By looking at this time series, it is easy to see that in the first half we have more zeros than ones and in the second ...
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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 ...
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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-...
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 ...
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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 ...
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0answers
44 views

Statistical test to assess the strength of the assertion “time series' values stayed the same” [duplicate]

The title somewhat gave my question away, but here goes... I have a time series of values covering a certain time span... If I chart it, I can visually conclude values roughly stayed the same. That ...
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170 views

Given sales data for a product, what is the best way to calculate the trend period for it?

I am looking for a statistical way to calculate an approximate in-trend period for a product from its sales data over a time period. Of course, in the 'in-trend' period, the sales of the product ...
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, ...
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
90 views

Which trend test should I use?

Sorry if this is a newbie question. For example, I have 5 groups and each group has different amount of people, and I got the face recognition score (in percentage, between 0 and 1) for all people in ...
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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 ...
0
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1answer
159 views

Analysing a genotypic 2X2 table instead of a 3X2 table

This could be a simple question to seasoned statistical genetics folks. I have delved into this doing an analysis for a friend on the sideline of a bioinformatics task I was helping her with. An ...
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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
77 views

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, time^...
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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 ...
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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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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 ...
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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 ...
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0answers
289 views

mixed results for stationarity tests and structural breaks

Following situation: I want to forecast a time series of the number of trucks on the motorway in some country. Here how the regular week looks like: I have data for 4 years and divide the huge time ...
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, ...
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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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 ...
3
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2answers
735 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 ...