Class Notes (807,239)
Psychology (7,610)
PSYB07H3 (39)
Lecture

# PSYB07 TUTORIAL NOTES

7 Pages
224 Views

School
University of Toronto Scarborough
Department
Psychology
Course
PSYB07H3
Professor
Douglas Bors
Semester
Fall

Description
TUTORIAL NOTES Population vs. Sample Population  entire collection of events/participants for the experiment Sample  a small representation of the population used for the experiment Random sampling method  every individual in the population should have an equal chance of being chosen (no inherent differences between sample and population; must do your best for sample to be random). *also known as external validity Random assignment  assign different condition of the study to each and different individual *also known as internal validity -when conduction an experiment, there are two variables: independent and dependent Independent Variable  something in our control, we can manipulate it Dependent Variable  depends on the independent variable (result of the study) i.e. effect of drug on memory No Drug Drug A Drug B Drug C Independent variable: selection of drugs, gender Dependent: memory scores -greater memory in drug C group -in general, males have higher memory than female scores Discrete variable  can take on limited number of values -drug and memory experiment is discrete (only four options for drugs and two options for gender) Continuous Variable  no restricted limits Categorical Data  divided into categories - drug and memory experiment is categorical Measurement Data  if data is being measured (against some scale) -therefore, memory scores: continuous (no limit, can take on any value) and measurement data Summation Notation ∑(x) = x + x + x + … + x 1. 2 12 22 3 2 n 2 2. ∑x = x +1x + 2 + … 3 x n (∑x) = (x + x + x + … + x ) 2 3. 2 1 2 3 n 4. ∑(x-y )  square y first, subtract it from x and add it all up ∑(x-y)  subtract first and then square the sum 5. Measures of Central Tendency Mean ȳ = ∑y/n ∑y = n ∙ ȳ Grand mean: ∑nȳ j j ∑n j *this is used when you don’t have the actual data Set of Scores: 1, 2, 5, 5, 5, 7, 7, 8, 8, 9, 9, 10, 10 th th th Median location = n + 1 = 12 + 1 = 6.5 position (median between 6 and 7 number) 2 2Median: 7.5 Mode: 5 -Median and mode are resistant to outliers (outliers draw man and median towards themselves). Measures of Spread Range  the difference between the lowest score and the highest score -sensitive to outliers Interquartile Range: first and last 25% of the scores are removed i.e. 1, 2, 5, 5, 5 | 7, 8, 8, 9, 9 | 10, 10, 11, 12, 15 | 16, 16, 16, 17, 20 Q1 median Q3 Range: 19 Median: 9.5 Interquartile Range (IQR): Q3-Q1 = 15.5 – 6 = 9.5 Variance Variance  average sum of the square deviance *the square is to ensure that when you add them up, you don’t get zero (y - ȳ) (y - ȳ) 1 -5 25 1 -5 25 2 -4 16 5 -1 1 5 -1 1 5 -1 1 7 1 1 8 2 4 8 2 4 8 2 4 9 3 9 9 3 9 10 4 16 ȳ = 6 2 2 0 116 Population variance: σ = (y - ȳ) n -this is used only when you have the population or when you don’t need to generalize the sample to the population Sample variance: s = (y - ȳ) n-1 -this is used when you have the population *assume that a question is asking for sample variance unless explicitly says population Why is n-1 used instead of n for the sample variance? Sample variance loses a degree of freedom  this is because if n is used instead, it underestimates the number of the population (so smaller than the population) and n-1 compensates for this  the value of the sample variance increases when the denominator is smaller as it becomes when it is n-1.Histograms Scores: 9, 9, 5, 8, 7, 2, 2, 8, 5, 10, 6, 9 Raw Score Frequency Cumulative Frequency Relative Frequency 0 0 0  0 0 1 0 0  0 + 0 0 2 2 2  0 + 0 + 2 2/12 3 0 2  0 + 0 + 2 + 0 0 4 0 2  0 + 0 + 2 + 0 + 0 0 5 2 4  0 + 0 + 2 + 0 + 0 + 2 2/12 6 1 5  0 + 0 + 2 + 0 + 0 + 2 + 1 1/12 7 1 6  0 + 0 +
More Less

Related notes for PSYB07H3

OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Join to view

OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.