Lecture 2 Flashcards

1
Q

4 important things in research question?

A
  1. question mark at the end
  2. indicate all the constructs being investigated
  3. contain the population
  4. verb that indicate the type of relationship proposed (associate, predict, difference)
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2
Q

3 verbal forms of relationship?

A
  • associate
  • predict
  • difference
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3
Q

in RQ:

“is there an association between studying research methods and happiness in psychology students?”

identify if this is a good RQ (use the 4 checklist for RQ requirement)

A
  1. question mark
  2. all constructs are listed explicitly: studying research methods and happiness
  3. population: psychology students
  4. verb: association
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4
Q

population vs sample

A

population: complete set of all individuals relevant to RQ. size: large. often unknown
sample: subset of individuals selected from population. size: known.

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5
Q

assumption in RQ regarding population & sample?

A

only one possible population and many possible samples drawn from that population

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6
Q

what is a construct?

A

a construct is an unobservable attribute of people that we use in both theories and research to explain human behaviour, cognition, affect

aka: attribute / theory
eg: need for cognition

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7
Q

what is a measure?

A

method for measuring people on a construct to obtain a score

aka: method
eg: need for cognition scale

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8
Q

what is a score?

A

numerical value on a construct measure assigned to an individual

aka: numerical value
eg: summed responses to items in need for cognition scale

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9
Q

what is raw observed scores?

A

values obtained directly from construct measure

often indicated by capital letter X, Y, etc

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10
Q

what is a deviation scores?

A

transformed value from raw observed scores

value obtained by subtracting mean score form each raw observed individual score

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11
Q

what does it mean when deviation score = 0?

A

means that raw score obtained is equal to mean score.

because deviation score is raw score subtracted by mean score

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12
Q

benefit of deviation score?

A

helps us to identify people below and above the mean.

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13
Q

characteristics of deviation score?

A
  • mean of deviation score = 0
  • normally lower case letter x or y
    standard deviation = standard deviation of raw scores
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14
Q

what is z score?

A

standardised score whereby the deviation score is divided by the standard deviation

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15
Q

characteristics of deviation score?

A
  • mean of z score = 0
  • standard deviation = 1
  • scaling is in standard deviation units
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16
Q

what is a standardised score?

A

more general version of z scores

value obtained by transforming raw score to have a PREDEFINED mean AND scaling for each unit of standard deviation.

mean and sd for standardised score are unknown. if mean = 0 and sd = 1, then it’s called z score.

hence, z score is a particular type of standardised score

eg: IQ scores (mean = 100, sd = 15)

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17
Q

what is continuous random variable

A

any numerical value within defined interval (eg: 0-100)

any possible real number within the range

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18
Q

what is discrete random variable

A

finite number of distinct values (eg: 1, 2, 3, 4, 5, 6)

typically indicated in integers. termed a ‘factor’ in R

also known as categorical variable (if it’s character by nature)

19
Q

what kind of variable is measured in this RQ:

“is there an association between subjective well being and optimism in students enrolled in RMHI and ARMP in 2019?”

A

swb and optimism are CONTINUOUS VARIABLE

20
Q

what kind of variable is measured in this RQ:
“is there an association between subject enrolment and type of student among enrolled students in RMHI and ARMP in 2019?”

A

subject enrolment and type of student are CATEGORICAL VARIABLE

21
Q

what differentiates the analysis involving continuous and categorical variables?

(hint: correlation / contingency table)

A
continuous = correlation to answer RQ
categorical = contingency table to answer RQ
22
Q

summary characteristic

A
  • our analysis to answer RQ produce summary characteristic
  • a kind of aggregation on individual scores in one or more variables to produce a single quantity (eg average)
  • eg: mean, sd
23
Q

2 types of summary characteristics

A

population parameter and sample statistics

how to distinguish???
look at whom they are referring to (population or sample)

24
Q

what is population parameter

A

aggregated summary characteristics involving ALL individual from a population

25
characteristic of population parameter
there is only ONE value of a population parameter
26
what is sample statistic
aggregated summary characteristics from single sample drawn from a population
27
characteristic of sample statistics
can have many sample statistics (one for each sample) sample statistics vary from one to the next hence sample statistics are themselves random variables. value of sample statistic is an estimate of the unknown population parameter.
28
2 kinds of distributions of scores
population distribution and sample distribution
29
characteristic of population distribution
there is only ONE | typically exist theoretically
30
characteristic of sample distribution
many, one for each sample
31
what is univariate distribution
distribution of one variable
32
what is bivariate distribution
distribution of 2 variables
33
correlation
measure of LINEAR SYMMETRIC association between two CONTINUOUS variables most commonly used: pearson
34
will it make a different which variable is assigned to x axis or y axis in correlation?
no. cor(X, Y) = cor(Y,X) hence, measure of association would be the same regardless of the variables assigned to which axis
35
what does it mean to have positive association
high scores on variable 1, high scores on variable 2
36
what does it mean to have negative association
high scores on variable 1, low scores on variable 2
37
what does it mean to have no association
variables are uncorrelated
38
what are the characteristics of correlation
- absolute value of correlation indicates strength of association (ignore negative or positive) - range is 0 - 1 - weak correlation: nearer to 0 - stronger correlation: nearer to 1
39
what is a correlation matrix
a table/matrix that indicates correlation of 2 or more variables. the rows indicate the set of variables column indicate the set of variables in the other variable.
40
what is correlation plot
table/matrix in which each individual cell refers to the correlation between 1 variable and another. colour intensity signifies the strength (darker means stronger) colour (red or blue) signifies direction (red is positive) helpful to see pattern (instead of numbers)
41
population vs sample correlation coefficient
p (rho) for population correlation | r for sample correlation (vary from one sample to the other). used as estimate for population.
42
what is the effect of sample size to sampling distribution?
shape and spread of distribution (aka graph) depends on the sample size. the bigger the sample size, the smaller the variability, less spread.
43
what is standard error
measure of variability of a sample statistic.