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:
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.
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
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 2829.0010.001.56952.22239 Trust- Parliament at Westmister 3011.0010.004.49152.30127 Most People Can Be Trusted 3059.0010.006.05302.15318 Feelings- Whites 2992.0010.007.40811.93979 Feelings- Blacks 2992.0010.006.39612.21780 Valid N (listwise) 2721
B coefficientStd. Error P Value (Constant)2.9830.1270.000 Feelings-Blacks-0.2190.0190.000 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 -0.219 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 0.219 points on the 0-10 scale.
Dependent variable: Feeling BNP B coefficientStd. Error P Value (Constant)1.7360.0940.000 Trust- Parliament at Westminster -0.0370.0180.044
Dependent variable: Feeling BNP B coefficientStd. Error P Value (Constant)2.5420.1270.000 Most People Can Be Trusted -0.1580.0200.000
B coefficient Std. Error P Value (Constant)1.2450.2520.000 Feelings- Whites 0.0590.0330.075 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