PSYC 305 Final || All Questions Answered Correctly.
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Course
PSYC 305 F
Institution
PSYC 305 F
Descriptive Statistics correct answers describe the properties of samples (or populations when they are completely known)
Inferential Statistics correct answers draw conclusions/make inferences about the properties of populations from sample data
variable correct answers -something that varie...
PSYC 305 Final || All Questions Answered Correctly.
Descriptive Statistics correct answers describe the properties of samples (or populations when
they are completely known)
Inferential Statistics correct answers draw conclusions/make inferences about the properties of
populations from sample data
variable correct answers -something that varies
-condition or characteristic that can have different values
nominal variable correct answers categorical
-classifies/identifies objects
Q: which restaurants do you prefer?
DICHOTOMOUS: 2 levels
ordinal variable correct answers categorical
-ranking data
Q: rank following restaurants according to quality
interval variable correct answers numerical
-rating data (equal distances)
Q: rate the following restaurants on their food quality
ratio variable correct answers numerical
-special kind of interval scale with a ZERO POINT
Ex: price, height, weight,
dependent variable (Y) correct answers -outcomes/responses
-predicted variables
Y depends on X
independent variables (X) correct answers -factors
-predictors, covariates
Y Depends on X
measures of central tendency correct answers mean, median, mode
measures of variation correct answers range, variance, standard deviation
mean correct answers sum of values divided by sample size
-x̅ for sample
-μ for population
-affected by extreme values
median correct answers exact middle value
,-if even number, take two middle numbers and average them
-not affected by extreme values
mode correct answers value that occurs most frequently
-not affected by extreme values
-used for numerical or categorical data
variation correct answers gives info about spread or variability of data
range correct answers difference between largest and smallest observations
variance correct answers average of squared deviations of values from the mean
standard deviation correct answers most commonly used measure of variation
-shows variation about the mean
-has the same units as the original data
shape of distribution correct answers symmetric or skewed
left skewed correct answers mean < median
right skewed correct answers median < mean
symmetric correct answers mean = median
normal bell-shaped distribution correct answers mean = median = mode
-dependent variable (Y) is usually normally distributed
-μ ± 1σ = 68% of population
-μ ± 2σ= 95%
-μ ± 3σ= 99.7%
hypothesis correct answers answer to a research question made about a population parameter
(not sample)
Ex: hamburgers make you fat
significance level (α) correct answers decide the area consisting of extreme scores which are
unlikely to occur if null hypothesis is true
-cutoff sample score for α is called the critical value
x^2 correct answers test score for frequency distributions
z correct answers one mean test statistic (if σ is known)
t correct answers one mean test statistic (if σ is unknown) or two mean statistic
ANOVA correct answers more than two means test statistic
, reject or not reject null correct answers if calculated value > 0.05 reject null
if p-value < 0.05 reject null
p-value correct answers significance level of test statistic
statistical significance correct answers if null is rejected, data is statistically significant
-does not mean effect is important or meaningful
-does not indicate effect sizes are useful for assessing importance
effect size correct answers standardized measure of magnitude of treatment effect
Ex:
1)pearson's correlation coefficient (r) or correlation ratio squared (r^2)
2) cohen's d
3) omega (w) or omega squared (w^2)
what is a small, medium, and large effect size? correct answers r=0.1 small
r=0.3 medium
r=0.5 large
Type 1 error correct answers False Positive
Reject null when it is true
Type 2 error correct answers False Negative
accept null when it is false
α correct answers probability of committing type 1 error (rejecting null when it is true)
β correct answers probability of committing type 2 error (accepting null when it is false)
1-β (power) correct answers probability of correctly rejecting a false null
single-mean z test correct answers to test whether a sample mean differs from a population mean
requirements:
-pop is normally distributed
-pop sd (σ) must be known
-sample must be SRS of pop
z-score correct answers follows standard normal distribution
purpose: transform any normal distribution to standard normal distribution
X-μ = deviation of a sample score from pop
σ: limits range of deviation
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