March 15, 2024, 1:46 p.m.



These FAQs are organized by topic; click a topic to view related questions and their answers. Alternatively, you can expand all topics and view them all at once.

How do I find out what's available on this website?

Scrolling down the home page reveals the descriptions of, and links to the site’s three main databases -Transatlantic, Intra-American and African names -  as well as all the special features. The five main sections of the website listed at the top right of the home page (Trans-Atlantic, Intra-American, African Names, Resources, About) plus a language choice, all repeated on every subsequent page, show the centrality of these databases and, along with their dropdown menus, allow the user to navigate easily between pages.

How do I move from one part of the website to another?

You can return to the Home page any time by clicking on the “Slave Voyages” located at the top left of every page. From any page of the website, you can move to another section by clicking on one of the five labels in the top navigation bar (or items in the drop-down menus associated with them). Each section draws on a distinctive color for its banner: blue-green (Trans-Atlantic), purple (Intra-American), green (African Names),  blue (Resources), and grey (About).

Can I reuse or republish any information or materials I find on this website?

The Voyages website supports education and research by making its information available for free. Much of the information is protected by copyright. An Attribution-Non-Commercial Creative Commons license governs much of the content on the site, including historical and imputed data found in the three main databases on the site. This license allows for the non-commercial republication of certain content on the site and the creation of derivate works, provided the Voyages website is appropriately credited as the original source. Some materials on the Voyages website, however, appear by permission of the copyright owners and require their approval before being republished. For a guide to the various content on the site, permissions governing their use, and examples of how to cite the original source, see the "Permissions to Reproduce" section of the "Legal" page.

How do I cite essays and texts found on the website?

That depends on the manual of style you are following. Most citations of materials on a website, however, involve name of author [when given], title of text [when given], name of the website, URL, and date accessed. For example, according to The Chicago Manual of Style Online, the introductory essay by David Eltis in the essays subsection of Trans-Atlantic should be cited as follows:

David Eltis, 'A Brief Overview of the Trans-Atlantic Slave Trade,' Slave Voyages: The Trans-Atlantic Slave Trade Database, https://www.slavevoyages.org/voyage/about (accessed April 27, 2018).

For more citation examples, see 'Permissions to Reproduce' on the Legal page of this website.

How do I cite a database found on the website?

The Chicago Manual of Style's 'Quick Guide' also provides an example of how to cite an item in an online database. For specific output or data selections, users should cite the URL generated by 'Save a search' at the star located at top right above the results panel. Pasting the URL into the website will always generate the same results.

What is the meaning of the abbreviation 'IMP' located after a variable?

This indicates that the variable is imputed rather than documented directly.  The value, however, is inferred by historians from data variables.  See 'Understanding the Database,' for an explanation of the assumptions and basis of all imputed variables.

Where can I see at a glance variables available for analysis in different sections of the website?

Go to Understanding the Database > Variable list. Look in the third, fourth, and fifth columns. The column 'Voyages' shows the number of cases that have information coded for each variable in the transatlantic database.

Where do I find bibliographies of studies of the slave trade on the website?

'Published secondary sources,' the fourth part of 'Sources' in Understanding the Database, a subsection of Methodology, provides a comprehensive bibliography of scholarly studies of the Atlantic slave trade.

How do I find documentation for a particular voyage?

Your starting point should be the 'Sources' for the voyage cited in both the Trans-Atlantic Slave and Intra-American databases. These are listed in the last of the 'Voyage variables' in Voyage detail, accessed by clicking on a voyage listed on the Results tab. 

How do I conduct a search for voyages? 

Searches are conducted by making selections from the eight groupings of variables listed along the foot of the colored banner: Year range; Ship, nation, owner; Itinerary, Enslaved People, Dates; Captain and crew; Outcome; Source. Clicking on any of these groupings will allow the user to select individual variables and impose search parameters. To complete the query, the user must click on “Apply.” This action runs the search and the selection of voyages that displays in the results panel under the colored banner. For the African Names and Images data, the query should be constructed via the search panel on the left-hand side of the results panel.

How do I display the parameters of my search?

When a search is created, a box containing a filter icon and "View all" appears at the bottom right of the colored banner.  Clicking on this will display the search parameters at the top left of the white space below the colored banner.

How do I restore the results panel to its pre-search condition?

Click on the box containing the message "Reset all" at the bottom right of the colored banner.

How do I save my search(es)?

At the right in the colored banner at the top of the page click on the "*" symbol and then "Save".  You may save as many queries as you wish though they will remain here only until the current session ends and should be copied elsewhere to preserve them for future use.  To restore a search, simply click on the appropriate "Load" box.  Or paste in an old url.

How do I select ship names, captains, owners and sources?

Click on "Ship, nation, owner" or "Source" in the colored banner of "Trans-Atlantic" or "Intra-American". This will open a box to enter the name or part name. Click on "Apply" and the program will list all records containing the sequence of letters you entered. To find voyages linked to a particular source first check the list of sources displayed at the foot of "Understanding the database." 

How do I extend the range of variables displayed under the 'Results Listing?

Clicking on 'Configure columns' at top right will allow you to add or remove variables to the display with one further click on the target variable.

Is there a way to know how many cases in the database have information relevant to a particular search?

After you apply your search criteria you can see how many voyages meet your requirements by viewing the number above the results panel. 

What can I do with the results of my search?

The first row beneath the colored panel comprises seven options for processing your data. "Results" allows you to look at your selection voyage by voyage - to see details of an individual voyage click on an entry; "Summary statistics" generates aggregated summaries of key variables in your selection; "Tables" and "Data visualization give the user the option of reorganizing her results in the form of tabular or graph format; "Timeline" allows the display of time trends that might be of interest; "Maps" displays the trans-Atlantic connections in the results, with the thickness of the path graphics reflecting the number of enslaved people transported (click on the path to see the actual number). "Timelapse" will run the selected voyages across the Atlantic with one black dot per ship (pause the run and click on a black dot to see the details of a particular voyage).

How do I print results?

In the results panel the download button at the top right will print the results of your query in CSV or Excel format.  "Summary statistics," "Tables," "Data visualization" and "Timeline" offer the same option.  

What do 'averages' calculated in Summary Statistics, Tables, and the Timeline mean?

An average is a value that is typical or representative of all values for the group of persons or things it describes. It is important to remember that the meaning of an average should be judged by the amount of deviation of particular cases around it. For four voyages landing 250, 280, 310, 360 slaves respectively, and for three voyages with 100 slaves and one voyage with 900, the average is the same: 300 slaves. The standard deviation is the clue to how much the average resembles particular cases in the group for which it is calculated. Divide the standard deviation by the average. The smaller the quotient, the closer particular cases are to the average. The larger the quotient, the more variation there is above and below the average.

How do I determine if a slaving voyage is typical or exceptional?

Compare statistics for the voyage, as shown in Voyage detail, to summary statistics for all voyages or voyages of the same type. All voyages is usually too large a reference group to be a meaningful unit of comparison. It is more revealing to determine if a voyage is typical of others under the same flag, or from the same period of time, or following the same route from a region in Africa to a region in the Americas.

Can the data be examined in larger units than single years?

By clicking on the "Year range" at the bottom left of the colored panel, the user can specify periods of any duration, but only one period at a time. In the tables tab in both Estimates and Search the Database, the user can choose to display a number of statistics about the slave trade in 5-year, 10-year, 25-year , 50-year, and 100-year periods. Click the desired period in the selection area for table rows. In Data visualization, choices for the x-axis variable include year of arrival of slaves, number of slaves emabarked and disembarked, and voyage times, and crew size.

What can be learned by graphing differences observed in tables?

Graphing can bring to the researcher's attention patterns that might not be observed simply scanning the statistics contained in a table. Tables also present the danger of tempting the researcher to exaggerate the importance of small differences. If differences are too small, or patterns too indistinct, to be clearly observed in a graph, they are usually not significant.

Data visualization offers the possibility to construct three kinds of graphs: XY, donut, and bar charts. When should I use each type?

In general, bar charts are appropriate for comparing two to ten categories that can be measured numerically; donut charts are appropriate for comparing percentages of a whole; and XY charts show the relationship, or correlation, between two numerical variables.

How do I construct a bar chart?

First, select "Bar chart" on the left of "Data visualization". Second, choose a categorical variable for the X (horizontal) axis from the dropdown menu. Third, select for the Y (vertical) axis a variable that can be measured for each category. Several series can be included in the graph if one wishes to do so, but they must be similar. Any series can be removed by clicking on the variable name. If the resulting graph is not satisfactory, rethink your specifications.

How do I make a donut chart?

A donut chart is a circular graph having radii dividing the circle into sectors proportional in area to the relative magnitudes, frequencies or percentages represented. Donut charts effectively depict percentages.

To make a donut chart in Data visualization, click on the appropriate button; enter under Sectors the variable whose values will represent circle of the donut; use the Values box to choose a variable to determine how the size of each segment will be measured.  Click on the variable name to select or remove a variable. It is important to choose a variable with a small enough set of values for the pieces of the donut to be more than thin slivers. 

How do I draw an XY graph?

An X-Y scatter plot consists of a line drawn between the co-ordinates of values of two numerical variables - one on the X (horizontal) axis, the other on the Y (vertical) axis. X-Y charts effectively display changes over time, with a year variable plotted on the x-axis. However, any two numeric variables that might be correlated can be plotted against each other on this type of chart, for example, Middle passage (days) and Percentage of slaves embarked who died on voyage. 

The Voyages Database and Estimates both have timelines. How do I use them to observe differences over time? Should trends look the same in both sections?

The timeline is a bar graph that functions similarly in Estimates and the Voyages Database. The main difference is that it shows only captives embarked and disembarked per year in Estimates, while it can describe annual change of a larger number of variables in the Voyages Database. For the latter, click on a variable in the selection box. The timeline for Estimates includes a chronology which illustrates how this graphic can be used to show the impact of critical events on the slave trade. Moving the cursor from left to right in the main graph area causes a bar to appear indicating year, and information for that year appears below the timeline. To view a segment of time in more detail, click and drag from the beginning to the end year of the desired period. Because estimates take into account voyages for which documentation is lacking, the number of embarked and disembarked slaves will be greater in its timeline than in the one for the transatlantic database, but trends will be similar.

What kinds of maps are found in the website?

The Introductory maps available via the home page link and the Trans-Atlantic dropdown menu provide a cartographical view of the history of the slave trade. The nine introductory maps are among the 187 included in the Atlas of the Transatlantic Slave Trade (New Haven, 2010).  Both the Trans-Atlantic voyages database and Estimates have maps which allow the user to picture the size and structure of the slave trade as defined by criteria of time, space, national carrier, and other variables in the data set. 

Is there any difference between maps in the Trans-Atlantic voyages database and in Estimates?

The icons and options for maps in both sections are similar, but there are two important differences. The Trans-Atlantic voyages database permits users to put names on maps corresponding to three levels of detail in labeling: broad regions, regions, and places or ports. In Estimates, only broad and specific regions appear on maps. Embarkation regions in Africa are the same in the two sections, but broad disembarkation regions are slightly different. In the Trans-Atlantic voyages database there are six: Europe, Africa, Brazil, the Caribbean, Spanish American Mainland, and Mainland North America. In Estimates, the Caribbean is further distinguished by the major powers holding slave colonies there: Great Britain, France, the Netherlands, and Denmark. Colonies in the Guianas are included in the Caribbean. Spanish Americas combines Spain's Caribbean colonies (Santo Domingo, Cuba, and Puerto Rico) with its mainland colonies, from Mexico to the Rio de la Plata basin. Specific regions within Mainland North America, the British, French, and Danish Caribbean, and the Dutch and Spanish Americas, are also defined somewhat differently in Estimates than in the transatlantic voyages database.

How are interactive maps affected by a change in search parameters?

Any change in criteria used to select transatlantic voyages also changes the representation of places of embarkation and disembarkation. These are linked by path graphics. Rolling over a path graphic and clicking gives exact statistics. Changing the time frame or the geographic reference automatically changes the width of the path graphics and the statistics revealed by clicking on a path. 

What is the function of plus and minus signs at the top left of the map? 

The icons enable the user to zoom in or out. Political and language labels appear only on the two lowest zooms.  As the zoom level changes, so do the path graphics, the labels, and the geophysical or historical background detail. There are a total of six zoom levels.

Do the background features of the map change with the user's choice of time periods?

The geophysical features remain constant but the boundaries of states and colonies shown correspond roughly to the year 1750.  

What features are shown on geophysical maps?

Within land masses, one can see rivers (albeit unlabeled) and coastline. Within the North and South Atlantic, the most important ocean currents are traced and labeled. The direction of currents is clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere.

What kinds of detail are displayed on the historical maps?

In Europe, the area of countries where voyages were organized are shaded. Except for Spain, labels of the names of slave trading nations are placed off adjacent coastlines.

In Africa, shaded areas show states, regions, and large population groups. The approximate area covered by each is shown by light grey borders, and the white labels in capital letters are the names of these territorial units. Labels in purple are for so-called ethnic groups not associated with territorial units. Regions of the coast, as defined by Philip Curtin and adopted on this website, are shown in large capital letters adjacent to the coastline to which they refer.

In historical maps of regions and ports in both North and South America, shaded areas represent the extent of colonization around 1750. 

Can I download results for further analysis using a spreadsheet?

Yes. There are buttons on most pages for downloading information or results from the page in a csv (comma delimited file). Simply click on the button. It will transfer the data file to your computer where you can import it into a spreadsheet program of your choice.

What parts of the Slave Voyages website can I download and how?

First, you can download any PDF file. Click on the link to open it. Acrobat reader provides an option allowing you to save the file to your hard disk. Second, data for most tables and graphs can be downloaded as a csv file by clicking on buttons for this purpose under the display of results in the main area of the page. Third, in the Downloads subsection of the Trans-Atlantic and Intra-American Databases, links are provided to enable you to download the full set of variables in the current as well as several earlier editions of the Trans-Atlantic Slave Trade SPSS Database, as well as the codebook for the SPSS versions. A csv equivalent of the current versions (Trans-Atlantic, Intra-American, and African Names) is also made available as well as a spreadsheet containing the basic calculations used to derive the interactive estimates database.   

What should I do if I find errors in how a variable or variables are coded for a particular voyage or set of voyages?

Correct them using the data entry form in Contribute, to be found in both Trans-Atlantic and Intra-American dropdown menus. the fourth subsection under 'The Database'. You will be required to register first. Once in you will be asked to choose between four types of submissions. The first is a new voyage. The second is 'Edit an existing voyage.' It has two columns, on the left there are data as presently entered, on the right the correct data that you propose instead. For variables that are already correct, you just need to click on 'copy.' A space is also provided for any notes about your revision of each variable. The third is merging voyages which appear to have been entered twice. The fourth is to recommend deletion of a voyage. It is particularly important to provide full information about the sources used to identify mistakes.

How do I make contributions to features of the website other than the databases (essays, images, bibliographies, links, documents)?

Rather than using the data entry form, contact voyages@emory.edu.

What kinds of essays are published on the website?

Presently, the essays subsection of Understanding the Database contains three types of contributions: interpretative essays, vignettes or biographical sketches about individuals transported on slave ships, and a research note. We will periodically change the contents of this section, adding longer and shorter essays, notes, reports on archives, projects about the enslaved people, and in general any kind of text for which the Trans-Atlantic or Intra-American Slave Trade Database is a major source. Users are invited to submit manuscripts to voyages@emory.edu.

What is the difference between the transatlantic database and the estimates database?

Statistics in the Voyages Databases are for slaving voyages for which documentary evidence has been found. Evidence of other voyages remains to be discovered. In some cases, it will never be discovered. An attempt has been made to systematically evaluate the completeness of the record of the slave trade for different national carriers in different periods of time. Statistics in Estimates take into account the incomplete nature of historical evidence and adjust figures derived from the transatlantic database upwards to provide an account of the actual volume of the slave trade. Estimates do not yet exist for the Intra-American traffic.

Are embarkation regions in Estimates and the Trans-Atlantic Voyages Database defined differently?

No. Both sections make use of Philip Curtin's widely used distinction of eight regions of the Africa where slaves were embarked for transportation to the Americas. These regions are segments of the African Atlantic coastline in Africa from Senegambia in the North to West Central Africa in the South, with an eighth region in South-east Africa. In the website, off-shore islands are grouped with the region to which they are closest in proximity: the Cape Verde islands and Madeira with Senegambia, the Banana islands and Bance island with Sierra Leone, the Guinea islands with the Bight of Biafra, St. Helena with West Central Africa (although slaves were only disembarked there), and the Indian ocean islands, the Mascarene islands, and Madagascar with Southeast Africa.

Are disembarkation regions in Estimates and the Voyages Database defined differently?

Yes. In the Trans-Atlantic and Intra-American databases, the Caribbean forms one broad region, and major colonies are specific regions within it, with ports at a third level of analysis of geographical variables. In Estimates, on the other hand, broad regions include five wholly or partly within the Caribbean, broadly distinguished by colonizer nations: the British and French Caribbean, the Danish West Indies, and the Dutch and Spanish Caribbean. Spanish American mainland is a separate broad region in both transatlantic and intra-American databases that cannot be found in Estimates. The other broad regions are common to both data and estimates: Europe, Africa, Brazil, and Mainland North America.

How does 'Search for Images' (the query box in 'Images') function?

Thumbnails of images that match the search criteria (a key term, a period of time, or one of the categories into which the images are organized) will appear in the main part of the window. The user can click on any of them for a full size image and commentary.

What kinds of information are displayed when one clicks on the thumbnail of an image?

Each image includes a brief description of its historical relevance, the creator and location of the original work and its date of creation, and links to related voyages.

Where do I find information on the website to put slave voyages into historical context?

Several resources are available on the Voyages website itself: essays and introductory maps in Assessing the slave trade, the chronology of key events in the history of the slave trade below the Estimates timeline, images in Resources, and the glossary with key terms used by historians of the slave trade. In addition, the list of Sources and links on the website, without pretending to be exhaustive, point the user towards some of the most important places to look for information.

Can't find the information you are looking for?

Please address unanswered questions to svopcom@googlegroups.com, and we will attempt to provide this information for you.