tables and figures biol 4001. tables and figures results of scientific studies in both primary and...

TABLES and FIGURES

BIOL 4001

TABLES AND FIGURES

• Results of scientific studies in both primary and secondary literature are summarized for presentation in appropriate Tables and Figures which should clearly show key findings.

Graph or Table?

• If the data shows pronounced trends that would make an interesting picture, use a graph. If no such trends exist, use a table.

Graph or Table?• With graphs, differences between

variables and groups are easily seen ("a picture is worth a thousand words”).

Graph or Table?

• Tables are preferred for presenting exact numbers.

Graph or Table?• Tables can accommodate information

that graphs cannot (such as lists of species with their collection sites).

General Rules for Tables and Figures

• Tables and Figures appearing in a paper are numbered in the sequence by which they are referred, starting with Table 1 or Figure 1.

• Both are referred to in the text.

Germination rates were significantly higher after 24 hr water soak than in the control (Fig. 1) .

General Rules for Tables and Figures

• Figure is abbreviated Fig. Table is not abbreviated.

DNA sequence homologies for the purple gene from the four congeners (Table 1) show a strong similarity, differing at most by 4 base pairs.

General Rules for Tables and Figures

• In addition to a name (Fig. X or Table Y), every figure or table has a title. The title goes above the body of the Table. Like titles of articles, they are a single, concise sentence. A legend goes below or beside a Figure. A legend may be one sentence or a few that concisely describe the figure.

Title

Legend

TABLES

Tables are essentially lists of numbers or text in columns, each having a column label (heading).

Tables are read from the top down.

Lines of demarcation (rules) run horizontally but never vertically.

Footnotes are used to clarify points in the table, and go below the body of the table.

FIGURES

Figures include graphs, diagrams, photos, drawings, schematics, maps, etc. The term "Figure" is the correct name for all of these different pictorial presentations.

(more correctly placed in legend)

Descriptive Legends

• Each figure will have an accompanying legend which describes the displayed results and should give other pertinent, clarifying information (key to abbreviations, sample size, statistical results, etc.).

• Enough information must be given so that the figure can be understood without reading the paper.

Types of Graphs

Line Graph

Plots of a series of related values that depict a change in Y as a function of X.

Shows trends and changes over time

Types of Graphs

Bar Graph

Used to compare the value of a variable (usually a summary value such as a mean) among two or more groups of measurements

Often have error bars to show the SD or SEM for each group

Types of Graphs

Histogram

A type of bar graph that shows the frequency of occurrence of data values for a sample variable.

Important in describing populations, e.g., size and age distributions

Types of Graphs

Scatterplot

Plots plots of X,Y coordinates showing the relationship between two variables

Shows if the variables change in value together in a consistent way. In this example, tree height appears to be dependent upon age.

Types of Graphs

Pie ChartUbiquitous in business and mass media, but rarely used in scientific publications because it is often difficult to compare different sections of a given chart to each other.

Numbers can be added (as in the example) to enhance readability

Dependent vs Independent Variable

• The independent variable is the characteristic manipulated by the scientist (or nature) during the experiment. By convention, it is placed on the X axis.

• The independent variable answers the question “What do I change?”.

Dependent vs Independent Variable

• The dependent variable is the characteristic affected by the manipulation of the independent variable. By convention, it is placed on the Y axis.

• The dependent variable answers the question “What do I observe?”.

Dependent variable

Independent variable