Questions tagged [environmental-data]
The environmental-data tag has no usage guidance.
45 questions
0
votes
0
answers
23
views
Need help with what test to run
Hi everyone,
I was monitoring environmental parameters of 4 different sites every month for an entire year. I calculated mean values for these parameters and their standard deviation. I want to see if ...
- 1
0
votes
1
answer
24
views
Can you measure correlation between only the seasonal components of 2 time series?
I have time series data for scorpion sting accidents and environmental data (rain). There is an upward trend in scorpion stings, but there is also a seasonal component which seems to match the rain (...
0
votes
0
answers
12
views
Adjustment in DLNM - case control setting
I have data in a case-control format with a 5-year lag of exposure. I want to adjust, in addition to the strata, for the number of monitoring stations used to calculate the exposure. The problem is ...
1
vote
0
answers
15
views
How do I treat regression when I know that relationships/coefficients will differ between individuals in my dataset?
I have a large dataset made up of 100 climate simulations. Each simulation runs over 100 years and for each year I calculate a handful of metrics (features). I'm interested in measuring how well these ...
- 111
1
vote
0
answers
18
views
Is the ETS function from forecast appropriate for skewed environmental time series data? does the time-series data need to meet certain criterion? [closed]
I have environmental data that is usually just analysed with the nonparametric man-kendall and sens slope, because it is skewed. Can the ETS function which picks what exponential smoothing model to ...
0
votes
1
answer
65
views
What statistical tests to use for multiple datasets?
I have calculated the species richness of mammals in 10 sites, for different variables. For example, I have the species richness of carnivores, omnivores, herbivores etc in one analysis group, and ...
- 1
0
votes
0
answers
25
views
Parametric or non parametric mixed effect models for very small sample size in ecological/soil data?
I am running an ecological/environmental experiment in a salt marsh with 5 experimental treatments and 3 replicate soil samples taken from each treatment. I have been taking measurements from these ...
- 1
1
vote
1
answer
86
views
Plotting PCA cordinates as composites of environmental parameters into NMDS ordination of species assemblages
I have conducted a PCA and identified that the principal components (PC) are not driven by a single environmental parameter but are affected by several for each PC. I was then advised to retrieve the ...
- 11
1
vote
0
answers
35
views
Confused about the censoring procedure in Helsel (2012) book
Reading Helsel STATISTICS FOR CENSORED ENVIRONMENTAL DATA USING MINITAB AND R,
at page xviii the author writes:
The Figure i4 shows concentration (y) levels versus distance (x)
downstream. What ...
- 145
1
vote
0
answers
33
views
Why is the fully-symmetric bidirectional case-crossover design biased and the semi-symmetric design not when there are time-trends in the exposure?
I am trying to understand why the fully-symmetric bidirectional case-crossover design is biased when there are time trends in the exposure and why the semi-symmetric design is not biased?
I have tried ...
- 371
1
vote
1
answer
122
views
Formal way to test if a non-linear approach is necessary to correlating environmental variables to NMDS ordination axes?
I've got a follow-up question to this post regarding correlating [non-]linear environmental variables to NMDS ordination axes.
My original plan was to use function ...
- 2,345
1
vote
0
answers
199
views
Interpreting NMDS environmental correlations in the context of spatial and temporal autocorrelation
Do I need to account for autocorrelation when assessing correlations of environmental variables on an NMDS (nonmetric multidimensional scaling) ordination of species data? If so, how?
Data + setup:
I'...
- 2,345
1
vote
0
answers
78
views
Can I use a GLM in R to analyse the relationship between time-series environmental variables?
I have a water quality sensor which is measuring various parameters every hour for one year in the same location. I would like to analyse the relationship between each of these parameters and ...
- 11
2
votes
2
answers
795
views
Need to scale environmental variables when correlating to NMDS axes?
I've created a Non-metric MultiDimensional Scaling (NMDS) ordination from a Bray-Curtis dissimilarity matrix. (Starting data were basal areas of various tree species across multiple research plots).
I'...
- 2,345
0
votes
0
answers
78
views
Is short vector length in PCA problematic? Why are my points so far from my vectors?
I am using PCA to examine the relationships between environmental factors of a couple of different types (physical properties, concentrations, relative abundance of genes). I have log-transformed the ...
2
votes
2
answers
392
views
How to calculate the value (wind direction) of "maximal effect" in a linear-circular correlation?
I am trying to evaluate the effect of wind direction (circular variable) on a dependent linear variable. I have used circular-linear regression to find the correlation coefficient between the two ...
- 31
1
vote
1
answer
34
views
What is the best correlation test to use when you want to compare two variables in a spatiotemporal context?
I have 9 sampling sites. I did the sampling in May, July, and September in the sediments and the water. So, I have 27 samples. I want to know if there is a linear correlation between total nitrogen ...
0
votes
0
answers
20
views
Adjusting decision thresholds for dataset with seasonality component
I am working with data on an infection which exhibits seasonality over the year - the disease tends to be more prevalent during the rainy seasons compared with dry seasons.
I'm looking at a binary ...
- 13
3
votes
1
answer
243
views
How the kurtosis value can determine the unhealthy event
I read a paper regarding air quality. The author mentioned that "The PM10 pollutant also shows the highest of kurtosis value, which indicates that it
appears most frequently in unhealthy ...
- 1,680
0
votes
0
answers
25
views
how to estimate the precipitation value from other relative data
I have climate data but the precipitation values are missing,
I would like to know if there is any formula used to estimate the precipitation value from the other recorded climate data: temperature, ...
- 153
1
vote
0
answers
38
views
How to choose the equally spaced values for temperature variable in R? [closed]
I am learning a distributed lag non-linear model. In that, I have to create a cross basis matrix first. For cross-basis, I need to specify the knots at equally spaced values of the temperature ...
- 11
1
vote
0
answers
55
views
Modelling community as random effect based on community-level exposure?
I am conducting community/school research to exploring the health impact of environmental exposures (e.g., air pollution). The exposure is predicted based on the address of the community/school ...
- 11
0
votes
0
answers
36
views
What is the best way to do a metanalysis for half-life?
I am working on a meta-analysis on pesticide degradation, where the quantity of interest is the difference in half-life in different environments. However I am in doubt of how to use the data; in all ...
1
vote
0
answers
84
views
How to analyse temporal variation in R---vigilance of birds
I am currently doing a project for my Bachelor degree, for which I study vigilance in birds. Obviously, I have to analyse the data statistically. However, I do not know where to begin since I do not ...
- 11
0
votes
1
answer
60
views
Correlation between heavy metals and community data
This is a preliminary study. I want to test whether the presence of heavy metals in surface water negatively affects the benthic macroinvertebrate community.
If it's the case, I'll continue the ...
1
vote
0
answers
17
views
finding the correlation between population density in a city and the city's PM 25 value
I am a high school student doing a report for my environmental science course, IB diploma.
My question is about how to find the correlation between two data sets.
My question of interest is whether ...
- 11
1
vote
1
answer
7k
views
Preparing data for cross-correlation time series
I have several data sets with air quality measurements for 20 locations. The measurements were done per second over a period of two weeks, 5 locations per period (because there were only 5 instruments)...
- 71
1
vote
0
answers
141
views
How to develop the EKC regression model?
I want to use the environmental Kuznets curve (EKC) to check the relationship between increase economic growth and environmental degradation, but I am faced with a challenge on how and where to build ...
4
votes
0
answers
3k
views
R vegan: RDA vs CCA, which test to answer my research question and which results to report?
(if my question should be cut up into sub-questions please let me know, since all those questions are related I decided to ask them here together as one long question)
Main question
As part of my ...
- 41
1
vote
0
answers
301
views
Arithmetic Mean Versus Geometric Mean for Environmental Measurements
The following comment was made by whuber in response to the question Which “mean” to use and when?
... in many cases the right mean to use is determined by the question we are trying to answer ...
- 1,071
1
vote
1
answer
63
views
Learning time series analysis in hydrogeology
Good morning,
I know there are some similar questions, but I'm asking anyway since I didn't find a suitable answer for what I'm looking for. I've got some daily hydrological data about a spring, ...
0
votes
1
answer
428
views
Structural change analysis validity in case of auto-correlated data?
I attempted to assess the "significance" of some environmental alteration through the identification of break points in a diagnostic time series (using R strucchange...
- 25
1
vote
1
answer
93
views
ANOVA, Linear Models, or something else?
I'm a rookie in statistics, but just wrapped up a semester of R analysis for natural resources. I'm working on my grad capstone and hoping I might be able to get some help generating ideas for ...
- 11
1
vote
0
answers
34
views
Impact of process efficiency on global warming potential
I am an environmental chemistry who is studying the impact of process efficiency improvements of a specific sector on global warming potential (GWP).
A have data from 288 firms and I have already ...
- 41
4
votes
0
answers
2k
views
Do I need to standardize environmental data before canonical correspondence analysis?
I have a dataset of 15 environmental variables (soil physical and chemical properties) and about 25 "species" variables for about 40 sampling sites. I want to do a CCA to analyse the effects of the ...
- 41
4
votes
2
answers
855
views
What to do if time series data remains autocorrelated?
Data:
I have 92 years of monthly climate data. One of my variables is a drought index (SPEI) ranging from -2 (dry) to 2 (wet).
All the data can be found here.
Data Structure:
...
- 2,345
2
votes
4
answers
776
views
Change Point Analysis for Environmental Data
Does anyone know of somewhere with resources on using change point analysis for determining environmental threshold values? Let me emphasize that this is NOT time series data. Change point analysis is ...
- 53
0
votes
0
answers
280
views
Change point analysis along an environmental gradient
I am looking at environmental data - habitat scores and stream conductivity (water quality measure) and looking to do some change point analysis in a set of 178 observations. As opposed to a more ...
- 53
1
vote
0
answers
191
views
Best method of analysis for negatively skewed longitudinal environmental data?
I have a dataset composed of a dependent variable (species percent cover) and a range of abiotic variables (salinity, temperature, pH, water movement etc). It is a longitudinal study, in which species ...
0
votes
0
answers
715
views
PERMANOVA Design
My aim is to quantify temporal change in community composition by measuring community composition through time at several plots using randomly placed quadrats. The idea would be to repeat surveys at ...
- 122
0
votes
1
answer
136
views
What kind of clustering algorithm for clustering samples according to OTUs
I have data in the following form:
...
- 285
2
votes
0
answers
353
views
Population genetics: analysis of allele frequency distribution along environmental gradients
Is there a software or a R package that does a simulation of spatial distribution of alleles? I'm interested in how a distribution of alleles of functional loci is shaped by a pattern of environmental ...
- 95
2
votes
1
answer
2k
views
How to compute a measure of distance between sites with continuous variables?
I have a dataframe with each row being a different site (51 sites), and each column being mean values of a different continuous environmental variable (19 variables).
I am trying to calculate a ...
- 21
2
votes
0
answers
805
views
Compositional analysis vs. Manly selection ratios
I am comparing habitat availability vs. use by a bird species using the R compana() function (package adehabitat) which uses Aebischer et al. (1993) method. It is a ...
- 21
1
vote
0
answers
463
views
What is best for comparing variability for environmental time series data: repeated-measures ANOVA or linear mixed models?
I've collected environmental data on the dust level using direct-reading instruments. The outputs from the instruments are concentrations recorded at each minute over 1 hour. The data collected at ...
- 51