31 materials found

Related resources: Input datasets 


Statistics - Interval-Wise Testing for omics data

Statistical Analyses for omics data Questions of the tutorial: - How to visualize high-resolution omics data in different groups of genomic regions? - How to evaluate differences in high-resolution omics data between groups of genomic regions? - How to detect locations and scales at which the...

Resource type: Tutorial

Statistics - Interval-Wise Testing for omics data https://tess.elixir-europe.org/materials/statistics-interval-wise-testing-for-omics-data Statistical Analyses for omics data Questions of the tutorial: - How to visualize high-resolution omics data in different groups of genomic regions? - How to evaluate differences in high-resolution omics data between groups of genomic regions? - How to detect locations and scales at which the significant effects unfold? Objectives of the tutorial: - Pre-process high-resolution omics data - Create pointwise boxplots corresponding to different groups of genomic regions - Perform the Interval-Wise Testing between two groups of genomic regions - Visualize and inspect test results - Detect relevant locations and scales
Assembly - Making sense of a newly assembled genome

DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome...

Resource type: Tutorial

Assembly - Making sense of a newly assembled genome https://tess.elixir-europe.org/materials/assembly-making-sense-of-a-newly-assembled-genome DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome Assembly is the process of reconstructing the original DNA sequence from the fragment reads alone. Questions of the tutorial: - I just assembled a genome. How does it compare with already sequenced genomes? - How do I find rearranged, inserted, or deleted regions? Objectives of the tutorial: - Identification of the most closely related genome to my new assembly - Perform sequence comparison to locate rearrangements - Identify genes located in deletions
Genome Annotation - Genome annotation with Prokka

Genome annotation is a multi-level process that includes prediction of protein-coding genes, as well as other functional genome units such as structural RNAs, tRNAs, small RNAs, pseudogenes, control regions, direct and inverted repeats, insertion sequences, transposons and other mobile...

Resource type: Tutorial

Genome Annotation - Genome annotation with Prokka https://tess.elixir-europe.org/materials/genome-annotation-genome-annotation-with-prokka Genome annotation is a multi-level process that includes prediction of protein-coding genes, as well as other functional genome units such as structural RNAs, tRNAs, small RNAs, pseudogenes, control regions, direct and inverted repeats, insertion sequences, transposons and other mobile elements. Questions of the tutorial: - How to annotate a bacterial genome? - How to visualize annoted genomic features? Objectives of the tutorial: - Load genome into Galaxy - Annotate genome with Prokka - View annotations in JBrowse
Genome Annotation - Genome Annotation

Genome annotation is a multi-level process that includes prediction of protein-coding genes, as well as other functional genome units such as structural RNAs, tRNAs, small RNAs, pseudogenes, control regions, direct and inverted repeats, insertion sequences, transposons and other mobile elements.

Resource type: Tutorial

Genome Annotation - Genome Annotation https://tess.elixir-europe.org/materials/genome-annotation-genome-annotation Genome annotation is a multi-level process that includes prediction of protein-coding genes, as well as other functional genome units such as structural RNAs, tRNAs, small RNAs, pseudogenes, control regions, direct and inverted repeats, insertion sequences, transposons and other mobile elements.
Variant Analysis - Mapping and molecular identification of phenotype-causing mutations

Exome sequencing means that all protein-coding genes in a genome are sequenced Questions of the tutorial: - What is mapping-by-sequencing? - How can it help you identify the causative mutation in phenotypic mutants isolated from genetic screens? Objectives of the tutorial: - Use joint...

Resource type: Tutorial

Variant Analysis - Mapping and molecular identification of phenotype-causing mutations https://tess.elixir-europe.org/materials/variant-analysis-mapping-by-sequencing Exome sequencing means that all protein-coding genes in a genome are sequenced Questions of the tutorial: - What is mapping-by-sequencing? - How can it help you identify the causative mutation in phenotypic mutants isolated from genetic screens? Objectives of the tutorial: - Use joint variant calling and extraction to facilitate variant comparison across samples - Perform variant linkage analyses for phenotypically selected recombinant progeny - Filter, annotate and report lists of variants
Sequence analysis - Genome annotation with Prokka

Analyses of sequences Questions of the tutorial: - How to annotate a bacterial genome? - How to visualize annoted genomic features? Objectives of the tutorial: - Load genome into Galaxy - Annotate genome with Prokka - View annotations in JBrowse

Sequence analysis - Genome annotation with Prokka https://tess.elixir-europe.org/materials/sequence-analysis-genome-annotation-with-prokka Analyses of sequences Questions of the tutorial: - How to annotate a bacterial genome? - How to visualize annoted genomic features? Objectives of the tutorial: - Load genome into Galaxy - Annotate genome with Prokka - View annotations in JBrowse
Epigenetics - Hi-C analysis of Drosophila melanogaster cells using HiCExplorer

DNA methylation is an epigenetic mechanism used by higher eukaryotes and involved in e.g. gene expression, X-Chromosome inactivating, imprinting, and gene silencing of germline specific gene and repetitive elements. Questions of the tutorial: - Why is a Hi-C analysis useful? - What is...

Resource type: Tutorial

Epigenetics - Hi-C analysis of Drosophila melanogaster cells using HiCExplorer https://tess.elixir-europe.org/materials/epigenetics-hi-c-analysis-of-drosophila-melanogaster-cells-using-hicexplorer DNA methylation is an epigenetic mechanism used by higher eukaryotes and involved in e.g. gene expression, X-Chromosome inactivating, imprinting, and gene silencing of germline specific gene and repetitive elements. Questions of the tutorial: - Why is a Hi-C analysis useful? - What is 'chromosome conformation capture'? - What are main steps in order to generate and plot a Hi-C contact matrix?
Variant Analysis - Calling variants in non-diploid systems

Exome sequencing means that all protein-coding genes in a genome are sequenced Questions of the tutorial: - How does frequency of mitochondrial polymorphisms change from mother to child? Objectives of the tutorial: - Using Galaxy's main site we will see how to call variants in bacteria,...

Resource type: Tutorial

Variant Analysis - Calling variants in non-diploid systems https://tess.elixir-europe.org/materials/variant-analysis-calling-variants-in-non-diploid-systems Exome sequencing means that all protein-coding genes in a genome are sequenced Questions of the tutorial: - How does frequency of mitochondrial polymorphisms change from mother to child? Objectives of the tutorial: - Using Galaxy's main site we will see how to call variants in bacteria, viruses, and organelles.
ChIP-Seq data analysis - Identification of the binding sites of the Estrogen receptor

ChIP-sequencing is a method used to analyze protein interactions with DNA. Questions of the tutorial: - How is raw ChIP-seq data processed and analyzed? - What are the binding sites of the Estrogen receptor? Objectives of the tutorial: - Inspect read quality with FastQC - Map reads with...

Resource type: Tutorial

ChIP-Seq data analysis - Identification of the binding sites of the Estrogen receptor https://tess.elixir-europe.org/materials/chip-seq-data-analysis-identification-of-the-binding-sites-of-the-estrogen-receptor ChIP-sequencing is a method used to analyze protein interactions with DNA. Questions of the tutorial: - How is raw ChIP-seq data processed and analyzed? - What are the binding sites of the Estrogen receptor? Objectives of the tutorial: - Inspect read quality with FastQC - Map reads with Bowtie2 - Assess the quality of an ChIP-seq experiments - Extract coverage files - Call enriched regions or peaks
Assembly - Unicycler Assembly

DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome...

Resource type: Tutorial

Assembly - Unicycler Assembly https://tess.elixir-europe.org/materials/assembly-unicycler-assembly DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome Assembly is the process of reconstructing the original DNA sequence from the fragment reads alone. Questions of the tutorial: - I have short reads and long reads. How do I assemble a genome? Objectives of the tutorial: - Perform Quality Control on your reads - Perform a Small genome Assembly with Unicycler - Evaluate the Quality of the Assembly with Quast - Annotate the assembly with Prokka
Transcriptomics - Visualization of RNA-Seq results with CummeRbund

Training material for all kinds of transcriptomics analysis. Questions of the tutorial: - How are RNA-Seq results stored? - Why are visualization techniques needed? - How to select our desired subjects for differential gene expression analysis? Objectives of the tutorial: - Manage RNA-Seq...

Resource type: Tutorial

Transcriptomics - Visualization of RNA-Seq results with CummeRbund https://tess.elixir-europe.org/materials/transcriptomics-visualization-of-rna-seq-results-with-cummerbund Training material for all kinds of transcriptomics analysis. Questions of the tutorial: - How are RNA-Seq results stored? - Why are visualization techniques needed? - How to select our desired subjects for differential gene expression analysis? Objectives of the tutorial: - Manage RNA-Seq results - Extract the desired subject for differential gene expression analysis - Visualize information
Proteomics - Peptide and Protein ID using OpenMS tools

Training material for proteomics workflows in Galaxy Questions of the tutorial: - How to convert LC-MS/MS raw files? - How to identify peptides? - How to identify proteins? - How to evaluate the results? Objectives of the tutorial: - Protein identification from LC-MS/MS raw files.

Resource type: Tutorial

Proteomics - Peptide and Protein ID using OpenMS tools https://tess.elixir-europe.org/materials/proteomics-peptide-and-protein-id-using-openms-tools Training material for proteomics workflows in Galaxy Questions of the tutorial: - How to convert LC-MS/MS raw files? - How to identify peptides? - How to identify proteins? - How to evaluate the results? Objectives of the tutorial: - Protein identification from LC-MS/MS raw files.
Sequence analysis - Genome Annotation

Analyses of sequences

Sequence analysis - Genome Annotation https://tess.elixir-europe.org/materials/analysis-of-sequences-genome-annotation Analyses of sequences
Variant Analysis - Exome sequencing data analysis

Exome sequencing means that all protein-coding genes in a genome are sequenced Questions of the tutorial: - How to identify the genetic variation with the use of exome sequencing? - What is the pipeline of the process of finding genetic variation which caused the disease? Objectives of the...

Resource type: Tutorial

Variant Analysis - Exome sequencing data analysis https://tess.elixir-europe.org/materials/variant-analysis-exome-sequencing-data-analysis Exome sequencing means that all protein-coding genes in a genome are sequenced Questions of the tutorial: - How to identify the genetic variation with the use of exome sequencing? - What is the pipeline of the process of finding genetic variation which caused the disease? Objectives of the tutorial: - Identification of the genetic variation using the exome sequencing - Using FreeBayes calls for variants generating - Variant analysis and GEMINI queries
ChIP-Seq data analysis - Identification of the binding sites of the T-cell acute lymphocytic leukemia protein 1 (TAL1)

ChIP-sequencing is a method used to analyze protein interactions with DNA. Questions of the tutorial: - How is raw ChIP-seq data processed and analyzed? - What are the binding sites of Tal1? - Which genes are regulated by Tal1? Objectives of the tutorial: - Inspect read quality with FastQC -...

Resource type: Tutorial

ChIP-Seq data analysis - Identification of the binding sites of the T-cell acute lymphocytic leukemia protein 1 (TAL1) https://tess.elixir-europe.org/materials/chip-seq-data-analysis-identification-of-the-binding-sites-of-the-t-cell-acute-lymphocytic-leukemia-protein-1-tal1 ChIP-sequencing is a method used to analyze protein interactions with DNA. Questions of the tutorial: - How is raw ChIP-seq data processed and analyzed? - What are the binding sites of Tal1? - Which genes are regulated by Tal1? Objectives of the tutorial: - Inspect read quality with FastQC - Perform read trimming with Trimmomatic - Align trimmed reads with BWA - Assess quality and reproducibility of experiments - Identify Tal1 binding sites with MACS2 - Determine unique/common Tal1 binding sites from G1E and Megakaryocytes - Identify unique/common Tal1 peaks occupying gene promoters - Visually inspect Tal1 peaks with Trackster
Assembly - De Bruijn Graph Assembly

DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome...

Resource type: Tutorial

Assembly - De Bruijn Graph Assembly https://tess.elixir-europe.org/materials/assembly-de-bruijn-graph-assembly DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome Assembly is the process of reconstructing the original DNA sequence from the fragment reads alone. Questions of the tutorial: - What are the factors that affect genome assembly? - How does Genome assembly work? Objectives of the tutorial: - Perform an optimised Velvet assembly with the Velvet Optimiser - Compare this assembly with those we did in the basic tutorial - Perform an assembly using the SPAdes assembler.
Assembly - Introduction to Genome Assembly

DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome...

Resource type: Tutorial

Assembly - Introduction to Genome Assembly https://tess.elixir-europe.org/materials/assembly-introduction-to-genome-assembly DNA sequence data has become an indispensable tool for Molecular Biology & Evolutionary Biology. Study in these fields now require a genome sequence to work from. We call this a 'Reference Sequence.' We need to build a reference for each species. We do this by Genome Assembly. De novo Genome Assembly is the process of reconstructing the original DNA sequence from the fragment reads alone. Questions of the tutorial: - How do we perform a very basic genome assembly from short read data? Objectives of the tutorial: - assemble some paired end reads using Velvet - examine the output of the assembly.
Introduction to Galaxy Analyses - From peaks to genes

Galaxy is a scientific workflow, data integration, and data and analysis persistence and publishing platform that aims to make computational biology accessible to research scientists that do not have computer programming experience. Questions of the tutorial: - How to use Galaxy? - How to get...

Resource type: Tutorial

Introduction to Galaxy Analyses - From peaks to genes https://tess.elixir-europe.org/materials/galaxy-introduction-from-peaks-to-genes Galaxy is a scientific workflow, data integration, and data and analysis persistence and publishing platform that aims to make computational biology accessible to research scientists that do not have computer programming experience. Questions of the tutorial: - How to use Galaxy? - How to get from peak regions to a list of gene names? Objectives of the tutorial: - Familiarize yourself with the basics of Galaxy - Learn how to obtain data from external sources - Learn how to run tools - Learn how histories work - Learn how to create a workflow - Learn how to share your work
Epigenetics - DNA Methylation data analysis

DNA methylation is an epigenetic mechanism used by higher eukaryotes and involved in e.g. gene expression, X-Chromosome inactivating, imprinting, and gene silencing of germline specific gene and repetitive elements. Questions of the tutorial: - What is methylation and why it cannot be...

Resource type: Tutorial

Epigenetics - DNA Methylation data analysis https://tess.elixir-europe.org/materials/epigenetics-dna-methylation-data-analysis DNA methylation is an epigenetic mechanism used by higher eukaryotes and involved in e.g. gene expression, X-Chromosome inactivating, imprinting, and gene silencing of germline specific gene and repetitive elements. Questions of the tutorial: - What is methylation and why it cannot be recognised by a normal NGS procedure? - Can a different methylation influence the expression of a gene? How? - Which tools you can use to analyse methylation data? Objectives of the tutorial: - Learn how to analyse methylation data - Get a first intuition what are common pitfalls.
Transcriptomics - Differential abundance testing of small RNAs

Training material for all kinds of transcriptomics analysis. Questions of the tutorial: - What small RNAs are expressed? - What RNA features have significantly different numbers of small RNAs targeting them between two conditions? Objectives of the tutorial: - Process small RNA-seq datasets...

Resource type: Tutorial

Transcriptomics - Differential abundance testing of small RNAs https://tess.elixir-europe.org/materials/transcriptomics-differential-abundance-testing-of-small-rnas Training material for all kinds of transcriptomics analysis. Questions of the tutorial: - What small RNAs are expressed? - What RNA features have significantly different numbers of small RNAs targeting them between two conditions? Objectives of the tutorial: - Process small RNA-seq datasets to determine quality and reproducibility. - Filter out contaminants (e.g. rRNA reads) in small RNA-seq datasets. - Differentiate between subclasses of small RNAs based on their characteristics. - Identify differently abundant small RNAs and their targets.
Transcriptomics - De novo transcriptome reconstruction with RNA-Seq

Training material for all kinds of transcriptomics analysis. Questions of the tutorial: - What genes are differentially expressed between G1E cells and megakaryocytes? - How can we generate a transcriptome de novo from RNA sequencing data? Objectives of the tutorial: - Analysis of RNA...

Resource type: Tutorial

Transcriptomics - De novo transcriptome reconstruction with RNA-Seq https://tess.elixir-europe.org/materials/transcriptomics-de-novo-transcriptome-reconstruction-with-rna-seq Training material for all kinds of transcriptomics analysis. Questions of the tutorial: - What genes are differentially expressed between G1E cells and megakaryocytes? - How can we generate a transcriptome de novo from RNA sequencing data? Objectives of the tutorial: - Analysis of RNA sequencing data using a reference genome - Reconstruction of transcripts without reference transcriptome (de novo) - Analysis of differentially expressed genes
Metagenomics - Analyses of metagenomics data - The global picture

Metagenomics is a discipline that enables the genomic study of uncultured microorganisms Questions of the tutorial: - How to analyze metagenomics data? - What information can be extracted of metagenomics data? - What is the difference between amplicon and shotgun data? - What are the difference...

Resource type: Tutorial

Metagenomics - Analyses of metagenomics data - The global picture https://tess.elixir-europe.org/materials/metagenomics-analyses-of-metagenomics-data-the-global-picture Metagenomics is a discipline that enables the genomic study of uncultured microorganisms Questions of the tutorial: - How to analyze metagenomics data? - What information can be extracted of metagenomics data? - What is the difference between amplicon and shotgun data? - What are the difference in the analyses of amplicon and shotgun data? Objectives of the tutorial: - Choosing the best approach to analyze metagenomics data - Selection of tools to analyze amplicon data or shotgun data - Visualisation of a community structure
Metagenomics - 16S Microbial Analysis with Mothur

Metagenomics is a discipline that enables the genomic study of uncultured microorganisms Questions of the tutorial: - What is the effect of normal variation in the gut microbiome on host health? Objectives of the tutorial: - Analyze of 16S rRNA sequencing data using the Mothur toolsuite in...

Resource type: Tutorial

Metagenomics - 16S Microbial Analysis with Mothur https://tess.elixir-europe.org/materials/metagenomics-16s-microbial-analysis-with-mothur Metagenomics is a discipline that enables the genomic study of uncultured microorganisms Questions of the tutorial: - What is the effect of normal variation in the gut microbiome on host health? Objectives of the tutorial: - Analyze of 16S rRNA sequencing data using the Mothur toolsuite in Galaxy
Proteomics - Peptide and Protein Quantification via Stable Isotope Labelling (SIL)

Training material for proteomics workflows in Galaxy Questions of the tutorial: - What are MS1 features? - How to quantify based on MS1 features? - How to map MS1 features to MS2 identifications? - How to evaluate and optimize the results? Objectives of the tutorial: - MS1 feature...

Resource type: Tutorial

Proteomics - Peptide and Protein Quantification via Stable Isotope Labelling (SIL) https://tess.elixir-europe.org/materials/proteomics-peptide-and-protein-quantification-via-stable-isotope-labelling-sil Training material for proteomics workflows in Galaxy Questions of the tutorial: - What are MS1 features? - How to quantify based on MS1 features? - How to map MS1 features to MS2 identifications? - How to evaluate and optimize the results? Objectives of the tutorial: - MS1 feature quantitation and mapping of quantitations to peptide and protein IDs.
Proteomics - Peptide and Protein ID using SearchGUI and PeptideShaker

Training material for proteomics workflows in Galaxy Questions of the tutorial: - How to convert LC-MS/MS raw files? - How to identify peptides? - How to identify proteins? - How to evaluate the results? Objectives of the tutorial: - Protein identification from LC-MS/MS raw files.

Resource type: Tutorial

Proteomics - Peptide and Protein ID using SearchGUI and PeptideShaker https://tess.elixir-europe.org/materials/proteomics-peptide-and-protein-id Training material for proteomics workflows in Galaxy Questions of the tutorial: - How to convert LC-MS/MS raw files? - How to identify peptides? - How to identify proteins? - How to evaluate the results? Objectives of the tutorial: - Protein identification from LC-MS/MS raw files.
Proteomics - Secretome Prediction

Training material for proteomics workflows in Galaxy Questions of the tutorial: - How to predict cellular protein localization based upon GO-terms? - How to combine multiple localization predictions? Objectives of the tutorial: - Predict proteins in the cellular secretome by using...

Resource type: Tutorial

Proteomics - Secretome Prediction https://tess.elixir-europe.org/materials/proteomics-secretome-prediction Training material for proteomics workflows in Galaxy Questions of the tutorial: - How to predict cellular protein localization based upon GO-terms? - How to combine multiple localization predictions? Objectives of the tutorial: - Predict proteins in the cellular secretome by using GO-terms. - Predict proteins in the cellular secretome by using WolfPSORT. - Combine the results of both predictions.
Sequence analysis - RAD-Seq to construct genetic maps

Analyses of sequences Questions of the tutorial: - How to analyze RAD sequencing data for a genetic map study? Objectives of the tutorial: - SNP calling from RAD sequencing data - Find and correct haplotypes - Create input files for genetic map building software

Resource type: Tutorial

Sequence analysis - RAD-Seq to construct genetic maps https://tess.elixir-europe.org/materials/analysis-of-sequences-rad-seq-to-construct-genetic-maps Analyses of sequences Questions of the tutorial: - How to analyze RAD sequencing data for a genetic map study? Objectives of the tutorial: - SNP calling from RAD sequencing data - Find and correct haplotypes - Create input files for genetic map building software
Sequence analysis - RAD-Seq de-novo data analysis

Analyses of sequences Questions of the tutorial: - How to analyze RAD sequencing data without a reference genome for a population genomics study? Objectives of the tutorial: - Analysis of RAD sequencing data without a reference genome - SNP calling from RAD sequencing data - Calculate...

Resource type: Tutorial

Sequence analysis - RAD-Seq de-novo data analysis https://tess.elixir-europe.org/materials/analysis-of-sequences-rad-seq-de-novo-data-analysis Analyses of sequences Questions of the tutorial: - How to analyze RAD sequencing data without a reference genome for a population genomics study? Objectives of the tutorial: - Analysis of RAD sequencing data without a reference genome - SNP calling from RAD sequencing data - Calculate population genomics statistics from RAD sequencing data
Sequence analysis - RAD-Seq Reference-based data analysis

Analyses of sequences Questions of the tutorial: - How to analyze RAD sequencing data using a reference genome for a population genomics study? Objectives of the tutorial: - Analysis of RAD sequencing data using a reference genome - SNP calling from RAD sequencing data - Calculate population...

Resource type: Tutorial

Sequence analysis - RAD-Seq Reference-based data analysis https://tess.elixir-europe.org/materials/analysis-of-sequences-rad-seq-reference-based-data-analysis Analyses of sequences Questions of the tutorial: - How to analyze RAD sequencing data using a reference genome for a population genomics study? Objectives of the tutorial: - Analysis of RAD sequencing data using a reference genome - SNP calling from RAD sequencing data - Calculate population genomics statistics from RAD sequencing data
Sequence analysis - Mapping

Analyses of sequences Questions of the tutorial: - What two things are crucial for a correct mapping? - What is BAM? Objectives of the tutorial: - You will learn what mapping is - A genome browser is shown that helps you to understand your data

Resource type: Tutorial

Sequence analysis - Mapping https://tess.elixir-europe.org/materials/analysis-of-sequences-mapping Analyses of sequences Questions of the tutorial: - What two things are crucial for a correct mapping? - What is BAM? Objectives of the tutorial: - You will learn what mapping is - A genome browser is shown that helps you to understand your data