---
title: "Chemistry Trend Analysis"
url: "https://help.esdat.net/en/article/chemistry-trend-analysis"
language: "en"
last_updated: "2024-11-27T04:44:23.570Z"
---

# Chemistry Trend Analysis

ESdat Supports Trend Analysis using the Mann-Kendall and Linear Regression statistical techniques.  ESdat also provides a "Last Value is Highest" identification.

Mann-Kendall is described originally in the following texts, and is also described in numerous textbooks describing stastical techniques for environmental data.  

-   Mann, H.B. 1945. Non-parametric tests against trend, Econometrica 13:163-171.
-   Kendall, M.G. 1975. Rank Correlation Methods, 4th edition, Charles Griffin, London.

The ESdat help documentation describes only the application of Mann-Kendall and Linear Regression techniques within ESdat.  For a description of these stasticical techniques ESdat users will need to refer to the above references or statistical textbooks.  ESdat applies Mann Kendall with a "one-tailed Mann-Kendall" approach, as opposed to a "two-tailed Mann-Kendall", which is the typical application.  

Within the Trend Analysis screen in ESdat users can select either Mann Kendall or Linear Regression as the technique, specify a Significance Level (A Significance Level of 0.05 relates to a Confidence Level of 95%; 0.1 relates to 90%) and the trend results will be shown.

Trends are always shown per analyte, for each Location & Well.   At least 3 data points in order to calculate a trend.  Trends are identified by:

-   TUp = Trending Up (shaded in orange)
-   TDn = Trending Down (shaded in yellow)
-   LH = Last Value Highest (shaded in orange)
-   NT = No Trend
-   Blank Cell = No data, or not enough data (<3 data points) to calculate a trend.

![](https://cdn-assets.productfruits.com/b089309e-ae64-4662-8e5b-78dd4292f148)

Users can select to show the trend stastics as well as the trend result, and clicking on a trend result will show a graph of the data, as shown below.   

![](https://cdn-assets.productfruits.com/f1e59782-9476-4c88-9ba7-5c54d55a0fe6)