population=
set of all individuals of interest in particular study
sample=
set of individuals selected from population
data=
measurements/ observations
data set=
collection of measurements or observations
datam =
singular measurement or observation
score/ raw score =
aka datam
singular measurement or observation
parameter=
is a value, usually a numerical value that describes a population
statistic=
is a value, usually a numerical value, that describes a sample
what is a parameter derived from?
measurements of the individuals in the population
what is a statistic derived from?
measurements of the individuals in the sample
descriptive statistics are...
used for 3 things
statistical procedures used to summarise, organise and simplify data
inferential statistics are...
techniques that allow us to study samples and make generalisations about the populations from which they were selected
sampling error
naturally occurring discrepancy, or error that exists between a sample statistic and corresponding population parameter
Correlational method:
two different variables are observed to determine whether there is a relationship between them
experimental method consists of 2 things:
1. manipulation
2. control
participant variables are
characteristics such as age, gender and intelligence that vary from one individual to another
environmental variables are
characteristics of the environment such as lighting, time of day and weather conditions
researchers use 3 basic techniques to control variables:
1. random assignment
2. matching
3. holding them constant
explain matching
give an example of matching
ensure equivalent environments/ groups
matching groups by ensuring every group has 60% females and 40% males
explain "holding them constant" .. give an example..
controlling variables.
e.g. only having 10 year old girls in experiment
non-experimental research:
examines the relationship between variables by comparing groups of scores
what are the IV and DV in a non-experimental research design?
IV: the variable that is used to create the groups
DV: participant's scores
the "independent variable" in a non-experimental study is called a ______. why?
quasi-independent variable
because it is not a true independent variable; it is not manipulated by the experimenter
what are contructs?
give examples
internal attributes/ characteristics. Not easily observed but useful for describing and explaining behaviour
examples: hunger, anxiety, intelligence
an operational definition
defines a construct in terms of external behaviours that can be observed or measured.
e.g. we can test IQ on a test.
a discrete variable
consists of separate, indivisible categories. no values can exist between neighbouring categories.
____ ____ are commonly restricted to whole, countable numbers - amount of students in a class, or children in a family.
discrete variables
continuous variables
have an infinite number of possible values that fall between two observed planes.
divisible into an infinite number of fractional parts.
it is very rare to obtain identical measurements when measuring a ____ ____
continuous variable
real limits
are the boundaries for scores represented on a continuous number line.
where is the real limit separating two adjacent scores located?
exactly halfway between the scores
each score has ___ real limits: what are these called?
2.
upper real limit, and lower real limit.
real limits apply to
any measure of a continuous variable even when the score categories are not whole numbers.
nominal scale=
having to do with names"
consists of a set of categories that have different names.
what does nominal scale measure?
E.g.......
it can label and categorise observations. But you cannot make any quantitative distinctions between observations
E.g. Male/Female. Room numbers.
What does ordinal scale measure? what can't it do?
E.g ....
Organised in fixed order"
Ordinal scale consists of a set of categories that are organised in ordered sequence. Measurements rank observations in terms of size or magnitude.
It can't allow you determine the size of difference between individuals.
E.g. Pl
Interval and Ratio scales:
consist of organised categories" plus: categories form a series of intervals that are all the same size.
Defining feature of interval scales:
zero point is arbitrary.
Does not indicate a zero amount of the variable being measured.
Defining features of ratio scales:
an absolute zero point.
With ratio scales, ratioes of numbers do relect ratios of magnitude.
what is the difference between a ratio scale and interval scale?
zero point is arbitrary in interval scale.
ratio scale has an absolute zero point.
a survey asks people to identify their age, annual income, and marital status. for each of these 3 variables, identify the scale of measurement that is used and whether the variable is continuous or discrete.
age and annual income are measures on ratio scales and are both continuous variables.
marital status is measures on a nominal scale and is a discrete variable
an english professor uses letter grades A, B, C, D to evaluate a set of student essays. what kind of scale is being used to measure the quality of the essays?
ordinal
the teacher asks students to identify their favourite reality television shows. the different shows make a _____ scale of measurement
nominal
a researcher studies the factors that determine the number of children that couples decide to have. the variable, number of children, is a ______ variable (discrete/continous)
discrete
when measuring height to the nearest inch, what are the real limits for a score of 68 inches?
67.5 lower limit and 68.5 upper limit
when measuring height to the nearest half an inch, what are the real limits for a score of 68 inches?
67.75 lower limit and 68.25 upper limit
X stands for
Y stands for
N stands for
n stands for
first score
second set of scores
number of scores in the population
number of scores in a sample
?X means:
the sum of all scores
following set of quiz scores: 10, 6, 7, 4. what is ?X? what is N?
?X = 27
N = 4
In equations:
_____ is done first
______ is done second
______ is done third
_______is done fourth
_______ is done last
1. parentheses
2. squaring
3. multiplying/dividing
4. summation using ?
5. addition and/or subtraction last
set of scores: 3, 1, 7, 4
Compute
?X
3+1+7+4=
15
set of scores: 3, 1, 7, 4
Compute
?X2
9+1+49+16=
75
set of scores: 3, 1, 7, 4
Compute
(?X)2
(15)2=
225
set of scores: 3, 1, 7, 4
Compute
?(X-1)
2+0+6+3
= 11
set of scores: 3, 1, 7, 4
Compute
?(x-1)2
4+0+36+9
=49
set of scores: 3, 1, 7, 4
Compute
?X-1
15-1
=14
X: 3, 1, 7, 4
Y: 5, 3, 4, 2
Compute ?XY and explain the equation
multiply X times Y for each score. The resulting products are listed int he 3rd column of the table:
15, 3, 28, 8. Finally, add the products.
= 54
Scores of 6,2,4,2:
Calculate:
a) ?X
b) ?X2
c) (?X)2
d) ?(X-2)
e) ?(X-2)2
a) 14
b) 60
c) 196
d) 6
e) 20
identify the first step in each of these calculations:
a) ?X2
b) (?X)2
c) ?(X-2)2
a) square each score
b) add scores together
c) -2 from each score
use summation notation to express each of the following:
a) add 4 points to each score then add the resulting values
b) add the scores then square the total
c) square each score, then add the squared values
a) ?(X+4)
b) (?X)2
c) ?X2
the term statistics is used to refer to methods for ____ ____ and ____ data
organising, summarising and interpreting
statistical methods can be classified into two broad categories: ____ _____, which organise and summarise data and ____ ____ which use sample data to draw conclusions about populations
descriptive statistics
inferential statistics
non experimental studies also examine _____ between _______ by comparing groups of scores, but they do not have the rigour of _____ ____ and cannot produce _____ ____ _____ relationships. instead of manipulating a variable to create different groups, a no
relationships
variables
true experiments
cause and effect explanations