What is a population? Give an example.
the entire collection of events in which you are interested.
Ex: student's scores, people's incomes, rats' running speeds
What is a sample? Give an example
A sample is a number of observations from the population studied and it is used to infer something about the characteristics of the population.
What are two aspects of randomness that are important to consider?
- 1) External Validity
- 2) Random assignment (internal validity)
Define external validity
The extent to which the sample reflects the population
Define internal validity
Internal validity is is the confidence that we can place in the cause and effect relationship in a scientific study.
In other words, is the effect found due to the experimental manipulation or pre-existing difference in the groups... etc.
A variable is a property of an object of event that can take on different values.
What are the main two types of variables?
1) Independent Variable
2) Dependent Variable
Define Independent Variable
an independent variable is the aspect of the study that is manipulated.
Independent variables can either be quantitative or qualitative and discrete or continuous.
Define Dependent Variable
- A dependent variable is the variable in the study that is being measured (or the data).
- Dependent variables are generally quantitative and continuous.
Define a Discrete Variable. Give an example.
A discrete variable is a variable which can only take on a limited number of values.
Ex: gender, nominal data (mostly).
Define continuous variable. Give an example.
A continuous variable is a variable in which any value between the lowest or highest points on the scale are possible.
Ex: Age, self-esteem score, (ordinal, ratio, interval)
Define Quantitative data. Give an example.
Quantitative data (aka measurement data) is the results of any sort of measurement.
Ex: score on a test, weight, height.
Define Qualitative Data. Give an example.
Qualititative data (aka frequency data, or categorical data) is the result of classifying or categorizing subjects, participants, or characteristics etc.
Ex: number of males and females, how many participants chose high anxiety, neutral or low anxiety
Define descriptive statistics. Give an example.
Descriptive statistics are statistical measures used to simply describe data.
Ex: measures of central tendency
What are the two primary division of the field of statistics?
- 1) Descriptive Statistics
- 2) Inferential Statistics
Define Inferential Statistics. Give and example.
Inferential Statistics are used to generalize your findings from your sample to the population.
A parameter is a measure that refers to an entire population.
A statistic is a measure that is calculated using a sample of data.
What are the four measurement scales?
- 1) Nominal
- 2) Ordinal
- 3) Interval
- 4) Ratio
Define the nominal measurement scale. Give an example.
Nomial variables do not scale items along a dimension, they are labels. All nominal data is categorical, and if numbers are involved they have no meaning other than they are convenient labels
Ex: hair colour, gender, political party
Define the ordinal measurement scale. Give an example.
The ordinal scale of measurement orders people objects or events along some continuum. We cannot calculate the differences between points on the scale.
Ex: Place in a race (1st-4th)
Define the interval measurement scale. Give an example.
An interval scale is one in which the differences between scale points can be discussed and / calculated. We cannot speak about ratios using an interval scale.
We cannot say that 20 degrees Celsius feels twice as hot as 10 degrees Celsius.
Define the ratio measurement scale. Give an example
A ratio scale has a true zero point (the point correspondes to the absence of the thing being measured). Not only do ratio scales have the properties of the other 3 scales, but they also allow us to speak about ratios. That board which is 20 cm is twice as long as the baord which is 10 cm long.
Ex: length, volumn, weight, time etc.