51 terms

dhatzimanolisTEACHER

data

Any pieces of information acquired through observation or experimentation.

reliable data

data that is the same when collected many times or by different people

valid data

Data resulting from a test that accurately measures what it is intended to measure

accuracy

How close a measurement or calculation is to the accepted value.

average or mean

The result obtained by adding several quantities together and then dividing this total by the number of quantities. It is an estimate of the "true" value of the measurement.

mode

The value that occurs most frequently in a given data set.

median

The middle number in a set of numbers that are listed in order

calibrated

Divided into units that correspond to a standard

significant figure

A prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement

uncertainty in measurement

The interval within which the true value can be expected to lie, with a given level of confidence or probability, e.g. "the temperature is 20°C ± 2°C, at a level of confidence of 95%."

The symbol ± is called "plus or minus", and in the example above means "plus or minus 2°C" - i.e. the temperature is most likely to be between 18°C and 22°C.

The "level of confidence" expresses how certain the scientists are of their claim that the temperature is in the range 18—22°C.

The symbol ± is called "plus or minus", and in the example above means "plus or minus 2°C" - i.e. the temperature is most likely to be between 18°C and 22°C.

The "level of confidence" expresses how certain the scientists are of their claim that the temperature is in the range 18—22°C.

standard deviation

A measure of the "spread" in the data.

standard error

An estimate in the uncertainty in the average of the measurements

quantitative

Data that is in numbers

qualitative

Data in the form of recorded descriptions rather than numerical measurements.

discrete data

This data is based on counts. Only a finite number of values is possible, and the values cannot be subdivided meaningfully

continuous data

Numerical data values that can be MEASURED

categorical data

Data that can be put into categories (like what color you prefer, your gender, or the state you were born in), as opposed to numerical data that can be placed on a number line.

histogram

A graph of vertical bars representing the frequency distribution of a set of data.

bar graph

A graph that uses horizontal or vertical bars to display data

binary data

Data is "either/or" or "yes/no". There are only two possible outcomes

ordinal data

A type of data that refers solely to a ranking of some kind

nominal data

data of categories only. Data cannot be arranged in an ordering scheme. (Gender, Race, Religion)

error

Errors lead to measurements being different to what they would otherwise be: the true value.

random error

These are statistical fluctuations (in either direction) in the measured data due to the precision limitations of the measurement device. These errors usually result from the experimenter's inability to take the same measurement in exactly the same way to get exact the same number.

systematic error

These are reproducible inaccuracies that are consistently in the same direction. Systematic errors are often due to a problem which persists throughout the entire experiment.

mistake

These are made in the calculations or in reading the instrument are not considered in error analysis. It is assumed that the experimenters are careful and competent!

trend

the overall direction taken by the data path

pattern

A repeating or growing sequence or design. An ordered set of numbers or shapes arranged according to a rule.

inversely proportional

One variable decreases as the other increases

directly proportional

The relationship between two variables whose ratio is a constant value

correlation

A measure of the relationship between two variables

linear

straight line

positive relationship or correlation

A linear relationship between variables, which shows that as the independent value increases so does the dependent value.

negative relationship or correlation

A relationship between variablesin which shows that as the independent value dcreases so does the dependent value.

no relationship or correlation

The value of the independent and dependent variable are scattered in the graph showing no pattern or trend.

extrapolation

Estimating a value outside the range of measured data.

interpolation

estimating a value within the range of measured data

type I error

An error that occurs when a researcher concludes that the independent variable had an effect on the dependent variable when no such relation exists; a "false positive"

type II error

An error that occurs when a researcher concludes that the independent variable had no effect on the dependent variable, when in truth it did; a "false negative".

scientific notataion

This is the way that scientists easily handle very large numbers or very small numbers.

independent variable

Factor in a controlled experiment that is deliberately changed; also called manipulated variable

dependent variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

chi-squared test

A statistical test that can be carried out on data that are in categories. It enables the investigator to determine how closely an observed set of data corresponds to the expected data.

correlation coefficient(r)

a statistical index of the relationship between two things (from -1 to +1)

range

The difference between the highest and lowest scores or measurements given.

ratio

A comparison of two quantities by division

sample

A small part or quantity intended to show what the whole is like.

parallax error

Error caused by not having your eye directly in line with the measurement

outliers

Abnormal data points; data points that do not fall in the same general pattern as the other data points.

resolution level of equipment

The smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.

e.g. a typical mercury thermometer will have a resolution of 1°C, but a typical digital thermometer will have a resolution of 0.1°C.

e.g. a typical mercury thermometer will have a resolution of 1°C, but a typical digital thermometer will have a resolution of 0.1°C.

precision

These are measurements are ones in which there is very little spread about the mean value.

Precision depends only on the extent of random errors - it gives no indication of how close results are to the true value.

Precision depends only on the extent of random errors - it gives no indication of how close results are to the true value.