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Qualitative vs. Quantitative Sampling What is the difference between: Quantitative and Qualitative Sampling?? Qualitative Sampling: Observational evaluation of some attribute. Quantitative Sampling: The measure or count of some attribute. Qualitative Sampling Observational, not direct measurement. Observer makes evaluation on condition or quantity. Often much quicker than quantitative sampling. Can be timely for making quick management decisions. May be more subject to observer bias than quantitative sampling. May be difficult to verify. Different Types of Qualitative Sampling Presence or absence of species or trait Site-condition evaluation Rough estimates of population size or attribute Photo interpretation Presence or Absence Plant survival after fire Rare plants Evaluate Spread of Disease

Qualitative Sampling Different Types of Qualitative Samplingpeople.oregonstate.edu/~rosenbed/FRWS3700/Lec-09 qualitative... · 1 Qualitative vs. Quantitative Sampling What is the

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Page 1: Qualitative Sampling Different Types of Qualitative Samplingpeople.oregonstate.edu/~rosenbed/FRWS3700/Lec-09 qualitative... · 1 Qualitative vs. Quantitative Sampling What is the

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Qualitative vs. Quantitative Sampling

What is the difference between: Quantitative and Qualitative

Sampling??

• Qualitative Sampling:Observational evaluation of some

attribute.

• Quantitative Sampling:The measure or count of some

attribute.

Qualitative Sampling• Observational, not direct measurement.• Observer makes evaluation on condition

or quantity.• Often much quicker than quantitative

sampling.• Can be timely for making quick

management decisions.• May be more subject to observer bias than

quantitative sampling.• May be difficult to verify.

Different Types of Qualitative Sampling

• Presence or absence of species or trait

• Site-condition evaluation• Rough estimates of population size or

attribute• Photo interpretation

Presence or Absence

Plant survival after fire

Rare plants

Evaluate Spread of Disease

Page 2: Qualitative Sampling Different Types of Qualitative Samplingpeople.oregonstate.edu/~rosenbed/FRWS3700/Lec-09 qualitative... · 1 Qualitative vs. Quantitative Sampling What is the

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Evaluation of Site Condition

•Poor grazing quality

•High fire potential

Assess Population

Size

Qualitative

Quantitative

Qualitative Data: Use of Photos

• Photo Documentation• Photo Plots• Photo Points• Remote Sensing – aircraft, satellite

All can trigger or guide management actions

Photo Documentation of Treatment Effects

Photo Documentation

of Invasive Weed

Encroachment

Edge encroachment

Dispersed encroachment

Photo Plot

Page 3: Qualitative Sampling Different Types of Qualitative Samplingpeople.oregonstate.edu/~rosenbed/FRWS3700/Lec-09 qualitative... · 1 Qualitative vs. Quantitative Sampling What is the

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Photo PointsMarch, 2002

April, 2002

May, 2002

Aug, 2002

Sep, 2002

Remote Sensing from Aircraft

• Normal photo image• Spectral Images – e.g., infra-red band• Digital Pixel Size: Often 10 cm to 30 m

Remote Sensing

from Aircraft

(infra-red)

Spring

Ant colonies (relative density)

Community boundaries

Remote Sensing

from Aircraft

(infra-red)

Juniper stand (density, tree dimameter)

Roads/trails

Satellite Remote Imaging

• Normal Image Photo• Multi-spectral bands• Pixel Resolution: 0.25

km - 10 km

Remote Sensing from Satellite

Fires in southeast USA

Volcanic Ash, Kodiak Is.

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Remote Sensing from Satellite

Dust storm in Afghanistan

First snow, Lake Baikal

Satellite Processed Images

Gross Primary Production (gross photosynthesis)

Determine at least one qualitative and one quantitative sampling method for each objective

1. Determine whether a specific toxic substance is leaking from an old tank into the Logan River.

2. Determine age structure of a pronghorn herd in central Wyoming.

3. Determine whether canvasback ducks are migrating through Cache Valley, Utah.

4. Determine whether ATV users have been driving off trail in Swan Flat.

5. Determine whether West Nile virus has reached Utah.6. Determine forage availability for sheep on a winter

allotment.7. Determine whether common dandelion has invaded

your lawn.8. Determine whether volcanic ash from Kodiak Island

volcano is reaching the Anchorage, Alaska airport.