School of
Integrative Biology

# Guidelines: Scientific Process

Main Conceptual Flow

Subconcepts

Biological Example: Moth Color

1. Observe/Question:

Moths are hard to see when they rest on certain backgrounds; they are cryptic.

2. Wonder/Speculate/Think:

I wonder if cryptic coloration of moths hides them from predators.

3. Generate Biological Hypothesis

1. If (hypothesis)
2. then (prediction)

Deduction (if....then logic)
Testability
Assumptions

If cryptic coloration hides moths from predation, then number of survivors will be higher for moths with non-altered coloration than moths with altered coloration.
Assumptions: 1) Predators can see altered coloration; 2) Investigators can see altered and non-altered equally.

4. Determine Experimental Design:

A. Independent Variable(s)
1. Number of independent variables
2. Number of treatments per variable

Experimentation:

1. Creation of variation in independent variable
2. Treatment - Control

Observation:

1. Use natural existing variation in independent variable

Experiment: alter wing coloration (with neon spray paint) = treatment;
no alteration of wing coloration = control
1 independent variable = coloration; 2 treatments = altered and non-altered

B. Dependent Variable(s)
1. Observation
2. Measurements/Counts

Categorical variable
Continuous variable

Dependent Variable = count of number of altered and non-altered moths recaptured and not recaptured

C. Replicates

Sample size per treatment
Relation to probability

Sample size = 100 moths/treatment

5. Collect Data:
6. Analyze Data:

A. Create Data File

B. Calculate Descriptive Statistics Types of Distributions (Frequency distributions)
1. normal
2. skewed
3. bimodal

Descriptors of Central Tendencies of Distributions
1. Mean
2. Dispersion
1. range
2. variance
3. standard deviation
(SD) = √variance
34% x 2 = 68% of data within 1 SD of mean
47.7% x 2 = 95.5% of data within 2 SD of mean

C. Graph Data Horizontal axis (x, independent variable)
Vertical axis (y, dependent variable)
Types of graphs
1. Box + Whisker (X , SD, range)
2. Bar (column) (independent variable = categorical)
3. Histogram of Frequency Distribution (continuous classes; tally frequency/class) D. Calculate Analytical (Comparative) Statistics What is question? What is hypothesis?
Choice of statistical test
Difference between distributions ⇒χ2 contingency test
Null Ho/Alternate H1
1. [symbolic format]
Ho: # non-altered recaptured = # altered recaptured
H1: # non-altered recaptured > # altered recaptured
Probability/Level of Significance Relate to SD + distributions Type I, II error α = .05 (p<0.05 of rejecting true Ho)
Interpretation of statistical output n.s. = non-significant; p > 0.05 Failure to reject null hypothesis (Ho)
7. Reach Conclusion: Fail to reject Ho; Support for H1 No proof No evidence that cyptic coloration hides moths from predators.
Assumption may have been violated. Predators may not see altered coloration as well as humans. Need to test that assumption.