Methods

Artifact

A portable object made or used by humans, typically of archaeological interest.

Feature

A non-portable structural element or context created by human activity, such as a building or soil layer.

1. EX: Tent rings, caches

Association

The relationship between artifacts or features found together in an archaeological context.

Portable artifact

An object that can be easily moved; can be unmodified or modified.

Unmodified artifact

A portable object that has not been changed from its original state.

• natural objects not modified in shape or size

Modified artifact (3)

A portable object that has been altered in some way; includes subtractive and additive modifications.

1. Subtractive: Artifacts modified by the removal of pieces

2. Additive: Several separate elements combined into a single object

3. Altered: chemical or molecular alteration of the raw material

Definition of a Site

A site is a dense cluster of artifacts

Population in Sampling

The entire group of individuals or items that a researcher aims to study.

Sample in Sampling

A subset of the population selected for study to infer conclusions about the whole.

Judgmental sampling

The archaeologist uses their own judgment, experience and expertise to choose where to look:

• Traditionally used by culture historians

  • Still the most commonly used method today

  • Major problem is the introduction of bias

  • If we only look where experience tells us sites will be, we will never know if our patterns are sampling bias or archaeological reality

Haphazard/grab sampling

One accepts whatever cases/sites one happens to encounter with no consideration of how representative they may or may not be:

• Accidental Sampling, is not likely to end up with a representative sample and can have an uncontrolled bias

  • e.g., go along roads in remote areas and accept it as

    representative

• Common prior to the 60s and 70s

Pros of Judgmental sampling

• Usually find stuff (the most exciting part of archaeology)

• Often the only practical method (location, expense)

Cons of Judgmental sampling

• Uncontrolled bias introduced

• Self-fulfilling, in that this method lessens chance of a “new” or unique discovery

Pros of Haphazard sampling

1. Quick and easy; requires no special planning.

2. Useful for pilot studies because it is an inductive method

Cons of Haphazard sampling

1. Often involves sampling less remote areas (e.g., where roads are not built)

2. Never know whether or not your sample is

   representative

   • Can have sampling errors

3. You could also strike out and get nothing

Probabilistic sampling

• Samples are drawn to conform to statistical probability theory

• Minimizes and eliminates (most) human subjective bias

• While this method is routine now, when it was first proposed in the late 1960s, there were rather mixed

Simple random sampling

Simple random sampling is used to understand an area or a site as a whole, not just the areas where we know something will be found:

• A probabilistic sampling technique in which each

  sample unit has a statistically equal chance for

  selection.

  • The areas to be sampled are chosen using a table (or

  computer generator) of random numbers

  1) observer bias is removed

  2) requires minimum assumptions about what is being studied

  3) easily implemented

  4) allows for the precision and reliability of the data to be assessed

Pros of Simple random sampling

• Eliminates or controls for bias

• Saves time, money and arch resources

• Relatively easily implemented

• Data may be analyzed statistically

• i.e., precision and reliability)

• Doesn’t require prior knowledge

• Minimizes assumptions about an area

Cons of Simple random sampling

• Luck of the draw may produce uneven coverage

• Takes no advantage of what we might already know

• May be difficult to undertake in certain environments

Systematic random sampling

Eliminates the potential of uneven coverage

• The first sample unit is chosen randomly, then other units are chosen at a fixed interval from the initially chosen unit

• To establish the width of the interval, find the ratio of the population size to the desired sample size: (K= N/n)

• Where K = the sampling interval, N= the population size (# of units), and n = sample size (# of units)

• Choose first K unit randomly, and then every Kth unit after that

• You need the random component to make it a probabilistic or statistical sampling technique

Pros of systematic interval sampling

• Easily implemented

• Easier to execute in the field

• Gives an even distribution of sample units across space

Cons of systematic interval sampling

• Doesn’t work well if there data is cyclical, periodic, or regular

• Which is seldom known beforehand

Stratified random sampling

Strata—just like subpopulations of soil layers, strata in statistics are subpopulations of the population of interest

• Judgement does play a part in defining strata

Stratification—controls for heterogeneity of the population by breaking the population into subpopulations, each of which is more internally homogeneous than the population as a whole

• If you can control heterogeneity you can decrease sample size but still maintain a sample indicative of the population.

• Use a variable that correlates with the research interest or hypotheses being tested

Procedure

1. Divide the population into subpopulations

2. Select a simple random sample within each subpopulation independent of the other subpopulation

Pros of stratified random sampling

• Ensures that all areas within a survey area

  are statistically sampled

  • No areas are missed because of random

  chance

  • Good for dealing with heterogenous

  populations

Cons of stratified random sampling

• • You introduce bias into the sample through

  the choice of strata

  • The strata you chose may have nothing to do

  with what you are wanting to sample

  • More set up time involved and prior

  knowledge

Surface reconnaissance

• Look for artifacts (including features) on the surface of the ground

• Easy to do in areas with minimal soil deposition (e.g., deserts)

• One way to see them is if the sediments have been disturbed:

  • Agricultural disturbance (i.e., plowing)

  • Tree falls

  • Cut banks along roads or streams

  • Rodent burrows

• Clearly, you must be aware of the geological age of the ground surface

  you are looking at

Coring

• This is often mechanized where the coring tool is

  pushed into the ground and then withdrawn with

  captured sediment remaining in the tube (used by

  soil scientists as well)

  • The tube is typically 2 to 15cm in diameter and the

  sediment is studied for any indication of culture,

  such as color changes, artifacts, etc.

Shovel testing

• Small test units excavated with a round nose shovel

  • Holes 30–40 cm in diameter and usually 40 – 50 cm deep; not practical below one meter

  • Provides a wider opening than an auger

Test pits

• Typically these are 1x1 m units

  • Rarely undertaken on the first phase of testing

  to find sites as it is more too time consuming

  • Excavate with a combination of shovel, trowel,

  and sometimes picks or mattocks

  • Provides an excellent way to facilitate a “soil

  profile” (the vertical dimension of excavation)

Augering

• Using a bucket auger (similar to a fence-post

  digger)

  • The probe is rotated into the ground to pull out

  sediment

  • They are used when you need to go deeper than

  one meter

Discovery probability factors

1. abundance, 2) clustering, 3) obtrusiveness, 4) visibility, 5) intensity.

Abundance

Frequency of a site type in an area

Clustering

Degree to which sites are aggregated

Obtrusiveness

Using a particular discovery technique, how detectable will a site be

Visibility

1. Site size

2. Artifact size

3. Artifact frequencies/densities

4. Size of exposure

5. Frequency of exposure

Non-Invasive Archaeological Methods

Using photographic and geophysical techniques that rely on some form of electromagnetic energy (e.g., light, electricity, heat, radio waves) to detect and measure the ground and below surface

Ground-penetrating radar

A non-invasive method that uses radar pulses to image the subsurface and identify structures.

• Radar pulses reflect back to the surface to detect

  potential buried features

Aerial and Satellite Reconnaissance

Using aerial or satellite imagery to assess geographical features and locate potential archaeological sites.

Soil Resistivity

Monitors the electrical resistance of soils near the surface of a site

Magnometer

Measures strength of magnetism between earth’s magnetic core and a sensor (can detect buried features)

Metal Detector

In archaeology, a metal detector is an instrument that uses electromagnetic fields to locate metallic artifacts beneath the ground, aiding in the identification and excavation of historical and cultural materials.