1. Data, Tables & Graphs
“…the kind of question you ask determines the kind of data you collect”
Handbook, p11

2. Data varies in… Types of data Manner of collection How much collected
population
sampling
“Understanding what kind of data you need to answer a particular question, and being able to know statistically that your results were not merely the result of chance, involve advance planning” p13

3. Statistics
Descriptive
Inferential

4. Descriptive Data trends or relationships
central tendencies (e.g distribution)
descriptive statistics (e.g. avg)
representations in form of graphs, photos, drawings, diagrams, maps, etc.

5. Types of Numerical Data
Discrete
Categorical (Nominal)
Ranking (Ordinal)
Continuous
Interval
Ratio

6. Handbook: Descriptive Data
Central Tendency
visualize w/ frequency distribution
considers only one variable
Which of the following forests would represent a uniform distribution?
Dispersion
values describe spread of data A B
C - neither

7. Frequency Distribution
Central tendency
Measure of the "typical" value in a data set. The mean & the median are two measures of central tendency.
Types of distributions:
or Poisson
or Uniform

8. Descriptive Statistics
Central Tendency: Reporting what usually happens
Mean
Median
Mode
Describing the dispersion:
Range
Std dev & variance

9. Normal Distribution 99.6% 95.4% 68.2% What is stdev?
Calculator or know formula
95.4%
68.2%

10. Means, Variability, Skew

11. Descriptive Data Provides a summary:
so that you can derive some meaning; necessary for interpretation of data
often first step required by stat test
to represent the original data to others
requires balance: derive meaning w/o “hiding” data

12. What happens to the data in a research notebook?
How do you choose what data to include in an article?

13. Precision
&
Accuracy

14. Presenting Scientific Data in graphs & tables
“A good illustration can help the scientist to be
heard when speaking,
to be read when writing.
It can help in the sharing of information with other scientists.
It can help to convince granting agencies to fund the research.
It can help in the teaching of students.
It can help to inform the public of the value of the work.”
Bullets, added for clarity
Mary Helen Briscoe
From How to Write… by Day

15. Tables, Graphs, or Neither
repetitive data
exact numerical values
Graph
interested in trend
shape reveals relationship
Neither
few determinations, many zeroes or 100%’s
std conditions or methods
negative data: graphs/table do not make data more important!
if able to be put into words in text
when data can be represented by one significant value (e.g. max or min)

16. General considerations
Illustrations should be intuitive
All symbols should have logical meaning
Summarize but represent data
Follow conventions of field or journal
Titles
Oral/poster vs. written

17. Titles: Oral vs. Written Formats

18. Arranging Tables Clear concise title
Like elements read down, not across
Horizontal, but no vertical lines
Explanatory footnotes; no excessive experimental detail
Avoid exponents (problems w/ conventions)

19. Arranging Graphs Keep simple & clear
Repetition can improve understanding
Do not include excessive info per graph
Avoid empty space
Legible font size
Think about the relationship you are trying to convey

20. What’s wrong with this graph/table? What features are good?
Look at the data summarized on the next two slides and make suggestions as to how the table or graph could be improved

21. Nitrate Introduced at 0 Hours
Control
50 mg/L
200 mg/L
100 mg/L
Not good:
2 titles?
title not informative
gray background, but then yellow hard to see if white background
Axes labels: Percent what? Time what units? Points floating w/in blocks vs ticks
Good:
redundancy w/ Color
29 hrs
48 hrs
72 hrs

23. Complete the following Google Form
Due by 11am Monday 10/15/18
(Completion after this time will be for partial credit)
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