Research in Psychology and Basic Concepts in Statistics Flashcards
Entire collection of events/observations we are interested in studying
Population
measurement taken from the population
parameter
measurements collected from the sample drawn from the population
statistic
denoted by the Greek letter (mu) µ.
population
*we must always clearly define the population we are
interested in.
observations drawn from the population and used to infer something about the characteristics of the population
samples
term used to refer to the population where samples are drawn from
sampling frame
things/observations/constructs that can be measured, controlled, or manipulated in research and can take on different values
variable/s
- variables that could have an effect on other variables and the one usually controlled in research
- may be either quantitative or qualitative and discrete or continuous
independent variable
- variable affected by the variations in the independent variable
- generally, but not always, quantitative and continuous
dependent variable
variables that can affect the outcome of the study, but which are not strictly part of the study
confounding variables
variables that can take on only a limited number of values (e.g., gender, high school class)
discrete variables
variables which can assume, at least in theory, any value between the lowest and highest points on the scale. (e.g., age and self esteem score)
continuous variables
data which are results of any sort of measurement
quantitative data/measurement data
frequency data or qualitative data
categorical data
may have an infinite number of values between adjacent units on the scale, all measurements made are approximate
continuous variable
____ are those values that are above and below the recorded value by one-half of the smallest measuring unit of the scale
real limits
Levels of Measurement of Variables/Scales
variables that allow for only categorization into named sets. individual items belong to some distinctively different categories, but there is no quantifying or ranking of items
ex. male or female, republican, democrat, independent
nominal
Levels of Measurement of Variables/Scales
variables which are ranked in order in terms of which has less and which has more of the quality represented by the variable, but not how much more
ex. socioeconomic status, military ranks, holmes and rahe (1967) scale of life stress
ordinal
Levels of Measurement of Variables/Scales
not only give rank but also quantify and compare the size differences (interval) between
ex. temperature, fahrenheit and celcius
interval
Levels of Measurement of Variables/Scales
variables that have an identifiable absolute of true zero point
ex. length, volume, time
ratio
statistics primarily aimed at describing or summarizing data into meaningful framework
Ex: measures of central tendency (mean,
median, mode), measures of dispersion (standard
deviation, variance), graphical representations of data
or distribution (histograms, graphs, scatter plot etc.)
descriptive statistics
(developed by John Tukey) - necessity of paying close attention to data and examining them in detail before invoking more technically involved procedures
Exploratory Data Analysis (EDA) or Exploratory Statistics
inferring hypotheses or educated guesses from the sample to the population with the use of statistical procedures
inferential statistics
Cornerstones of Research
measures what is supposed to be measured in research
validity
Cornerstones of Research
replicability of findings in research
reliability
Cornerstones of Research
refers to whether or not experimental or research results can be generalized to a real-world situation
external validity
Cornerstones of Research
manipulation of variables in research has led to an observed/desired difference
internal validity
Cornerstones of Research
a formal way of expressing a question as a prediction that can be tested
hypothesis
Cornerstones of Research
hypothesis that states that there will be no effect of the independent variable on the dependent variable
null hypothesis
__ or __ stands for the variable measured
X or Y
___ stands for the total number of subjects or score
N
___ is the ith score, where i can vary from 1 to N
Xi
pronounced as X-bar
Mean
Greek letter called “Sigma” or “summation of” or
“add up” or “take the sum of.
Σ
therefore means “add up all the scores in X.
∑X
sum of the squared scores
∑X²
sum of the X scores, quantity squared.
(∑X)²
