Assessment plots and statistical analysis

This report provides details of the assessment of alpha-HCH concentrations in common shrimp at station BCP.

• Timeseries metadata. Key information about the timeseries.
• Assessment plot. The fitted trend (solid line) with pointwise 90% confidence bands (grey shaded areas). The trend is plotted on the log scale, with the axis labels back-transformed for ease of interpretation. The points are the annual medians of the individual log concentration measurements.
• Trend with data. The fitted trend with pointwise 90% confidence bands. The points are the individual concentration measurements, with a < denoting a less-than value.
• Auxiliary data. The individual concentration measurements with supporting information: mean length of the individuals in the sample; dry weight (%) of the sample; lipid weight (%) of the sample.
• Assessment (related compounds). Assessment plots for all the compounds in the same chemical group.
• Data (related compounds). A scatter plot matrix of the individual concentration measurements for all the compounds in the same chemical group.

Timeseries metadata

• OSPAR region: 2
• Region: Southern North Sea
• Station code: BCP
• Station name: BCP
• Station latitude: 51.33
• Station longitude: 2.83
• Media: biota
• Species latin name: Crangon crangon
• Species common name: common shrimp
• Matrix: tail muscle
• Determinand code: HCHA
• Determinand name: alpha-HCH
• Units: μg kg^-1 lipid weight
• Extraction: 15 February 2019

Assessment plot

Trend with data

Auxiliary data

Assessments (related compounds)

Data (related compounds)

Statistical analysis

Trend assessment

Analysis of variance

                Df      AIC     AICc   Log lik Deviance     Chisq Chi df Pr(>Chisq)
mean             1 204.5347 206.7847 -99.26734 198.5347        NA     NA         NA
linear           2 201.9493 206.5207 -96.97464 193.9493 4.5854093      1 0.03224527
smooth (df = 2)  3 198.4669 206.8003 -94.23347 188.4669 5.4823321      1 0.01920961
smooth (df = 3)  4 199.6460 214.0460 -93.82299 187.6460 0.8209623      1 0.36489896

Change in log concentration

              Year start Year end  Fit start   Fit end    Change Std error         t   Pr(>|t|)
overall             1997     2013  0.1113085 -3.522523 -3.633832  1.606903 -2.261388 0.05006289
last 20 years       1998     2013 -0.1309469 -3.522523 -3.391576  1.499776 -2.261388 0.05006289

Status assessment

No assessment criteria