SCI110: Data Collection and Classifying Data

Flashcards on Data Collection and Classification

Protocol (Data Collection)

A plan established and documented that explains exactly how the data will be obtained, which will include operational definitions.

Pilot Study

A small test run of the study protocol used to check that the protocol is appropriate and practical, and to identify (and hence fix) possible problems with the study design or protocol.

Questionnaire

A set of questions for respondents to answer.

Leading Question

A question that may lead respondents to answer a certain way due to its wording or framing.

Double-Barreled Question

A question that touches upon more than one issue, yet allows only for one answer.

Non-Response Bias

Bias that occurs when individuals selected for a sample are unwilling or unable to participate, leading to a skewed representation of the population.

Response Bias

Tendency of a person to answer questions on a survey untruthfully or misleadingly.

Recall Bias

Systematic error caused by differences in the accuracy or completeness of the recollections retrieved (recalled) by study participants regarding events or experiences from the past.

Quantitative Data

Mathematically numerical data: the numbers have numerical meaning, and represent quantities or amounts. Quantitative data generally arise from counting or measuring.

Discrete Quantitative Data

Quantitative data that has possible values that can be counted, at least in theory.

Continuous Quantitative Data

Quantitative data that has (at least in theory) an infinite number of possible values between any two given values.

Qualitative Data

Data that is not mathematically numerical data: it consists of categories or labels.

Levels (Values) of a Qualitative Variable

The names of the distinct categories of a qualitative variable.

Nominal Qualitative Variable

A qualitative variable where the levels do not have a natural order.

Ordinal Qualitative Variable

A qualitative variable where the levels do have a natural order.

Distribution

Of a variable describes what values are present in the data, and how often those values appear.

Parameter

A number, usually unknown, describing some feature of a population.

Statistic

A number describing some feature of a sample (to estimate an unknown population parameter).

Right (Positively) Skewed

Most data are smaller, with some larger values.

Left (Negatively) Skewed

Most the data are larger, with some smaller values.

Symmetric Data

Approximately equal numbers of values are smaller and larger.

Bimodal Data

The distribution has two peaks.

Sample Mean

Estimates the population mean.

Sample Median

Estimates the population median.

Standard Deviation

Approximately, the average distance of the observations from the mean.

Interquartile Range (IQR)

The difference between the third quartile (Q3) and the first quartile (Q1), representing the range of the central 50% of the data.

Outliers

‘Unusual’ observations: those quite different (larger or smaller) than the bulk of the data.