Presentation on theme: "Office Hours: Thursday 1.30-2.30pm FW102. Null Hypothesis is a hypothesis which the researcher tries to disprove, reject or falsify Example: Does gender."— Presentation transcript:
Office Hours: Thursday pm FW102
Null Hypothesis is a hypothesis which the researcher tries to disprove, reject or falsify Example: Does gender influence the salary of a British worker? What is the Null Hypothesis? There is no association between gender and salary in UK.
Men % Women % Labour 75 BNP25
To find out if there is a significant association between the variables Calculates Expected frequencies (when Null Hypothesis is true) and compares them with the data we have (Observed Frequencies)
Same logic with Chi square test: Find the expected values when there is no association between the variables and compare them with the actual data we have. But use t-test when we have continuous variables (real numbers)
Shows difference between expected values when null hypothesis is true & the observed values If the t-value is close to or greater than +/-2, then the relationship is usually significant at what is called the.05 level.
R 2 ranges from 0 to 1 0 explains nothing 1 perfect association So if R 2 is 0.50, we can say that 50% of the variance in Y can be explained by the variance in X Or, you make 50% less errors when guessing Y by knowing X, as compared to guessing Y when not knowing X
(Simple regression equation) Y= a + b X
Intercept or a, the point where the line cuts the Y axis Slope of the line or b, the amount of change in Y that you get if X increases by one unit
Possible reasons for voting for Far-right parties (BNP) racist sentiments political alienation (public dissatisfaction with the working of democracy) social alienation What do you think? Which one is the main reason?
How much do you trust the Parliament at Westminster? political alienation On balance, would you say that most people can't be trusted or that most people can be trusted? Social alienation how do you feel about black and white people? Racist sentiment
political alienation There is no association between voting for BNP and the level of trust in the parliament Social alienation There is no association between voting for BNP and trusting people Racist sentiment There is no association between voting for BNP and feelings about black and white people
NMinimumMaximumMean Std. Deviation Feelings_BNP Trust- Parliament at Westmister Most People Can Be Trusted Feelings- Whites Feelings- Blacks Valid N (listwise) 2721
B coefficientStd. Error P Value (Constant) Feelings-Blacks a Dependent Variable: Feelings_BNP
THREE STEPS 1-SIGNIFICANCE OF THE ASSOCIATION The relationship between X (feelings for blacks) and Y (support for BNP) is significant at the 0.05 level (we can reject the null hypothesis of no association). 2-DIRECTION OF THE ASSOCIATION The b coefficient of is negative, indicating that the people who have positive feelings towards black people tend to have lower levels of support for BNP. 3- MAGNITUDE
3-MAGNITUDE OF THE X EFFECT For every percentage point increase in X (positive feelings towards black people), the level of support for BNP (Y) will decrease by points on the 0-10 scale.
Dependent variable: Feeling BNP B coefficientStd. Error P Value (Constant) Trust- Parliament at Westminster
Dependent variable: Feeling BNP B coefficientStd. Error P Value (Constant) Most People Can Be Trusted
B coefficient Std. Error P Value (Constant) Feelings- Whites Dependent Variable: Feelings_BNP
Multivariate Analysis: Testing Hypotheses Testing hypotheses with OLS regression Modelling in political science, multiple relationships between variables, interpreting OLS regression analysis Check out the moodle for readings