Scientific Method: HO vs. HA

Types of Studies: Experimental vs. Observational

Science & Study Basics- Overview

Ecological Methodology LEC-01a Althoff

INVENTORY & MONITORING

EVALUATION OF METHODS

EXPERIMENTAL

ANALYSIS: Trends/Baseline

INTERPRETATION

Scientific Method

Observation(s)

Question

Hypothesis

Prediction

Test:Experimental or

Additional observation

Test does _______support hypothesis:revise hypothesis or

pose new one

Test does _______hypothesis: make

additional predictions and test

them

Activity: Put these in proper order• Conclusion

• Experiment

• Hypothesis

• Observation(question)

• Theory

Some important terms

• _______ = sample unit left as “normal” or untreated

• _______ = sample unit that something “different” is done to it

• _______ = assumes no bias due to human subjectivity

• __________________ = independent variable• __________________ = dependent variable

Observational vs. Experimental Studies

• Observational: no controls (usually), trying to determine basics, learn patterns, trends, characteristics

• Experimental: control (usually), have basic knowledge of subject that enables one to “separate” into treatment groups

Hypothesis

• = null hypothesis….essentially says “no differences”

• = alternative hypothesis….essentially says “found differences”…with statisticalevidence to support that

Observational vs. Experimental Studies

• Observational: generally summarize data using _____________ statistics

• Experimental: determine if differences between treatments are “real” using _______________ statistics

Statistics • Descriptive statistics:

central tendency: mean, median, modespread: range, variance, standard deviation, standard errorrelationship: correlation (Pearson, Spearman)

• Inferential statistics:parametric: t-test, F-test, Analysis of Variance

(ANOVA), chi-squarednon-parametric: sign test, Kruskal-Wallis test,

Friedman test

• Models: Akaikae Information Criterion (AIC), Structural Equation Modeling (SEM)

Quail Eggs: Does Size Matter?• Not all eggs laid are the same….can vary by:

1) weight/mass2) yolk composition (protein & lipid

%)3) albumen composition (protein & water

%) 4) shell thickness

Quail Eggs: Key components

23

Pre-incubation Mid-incubation

Quail Eggs: Does Size Matter?• Normally take 23-24 days to hatch from start of

incubation

• Young born are __________…meaning they are “ready” to go (aka leave nest) within 6-24 hours after hatching

• Eggs must be kept at 99-100 oF (99.5 oF best) for the duration of the incubation period

• 3 ways for us to “check” on development:1) _______ eggs (expect weight will

decrease) 2) _______ eggs (expect air space to increase) 3) _______ eggs (expect “light”/”dark” areas)

Quail Eggs: Checking Egg Status

• Weigh – using digital platform scale

Quail Eggs: Checking Egg Status

• Float – in beaker of water Sink Semi-float Float

Quail Eggs: Checking Egg Status

• Candling

The “Study” Design

Starting with 100+ eggs

Placing in incubator with egg turner

Basics….

• Overall, eggs pre-incubation weighed from________________ grams

• To have “clear separation” of small vs. large eggs, will consider only eggs weight

11.3 g or less as _________12.4 g or greater as ___________

• Response variable: hatch within 24 hours of first hatch (= H24)

_______ or less ____ or greater

Hypothesis & Statistical Test

• H0 - No difference in H24 between small and large eggs

• HA - Difference in H24 between small and large eggs

• Evaluate using Chi-Squared (X2)

Hatch in H24

Small eggs (<11.3)(N = 28)

Large eggs (<12.4)(N = 31)