| { | |
| "original_study": { | |
| "claim": { | |
| "hypothesis": "On the economic policy dimension, the number of parties in the party system is positively associated with policy dispersion.", | |
| "hypothesis_location": "section Predictions of spatial theory, it is also discussed in the abstract and introduction", | |
| "statement": "The authors find that as the number of parties in the system increases, party dispersion increases and the effect is statistically significant for both policy dimensions (coefficient on log count of parties in system term = 0.39, robust SE clustered by country = 0.14, coefficient falls within a 95% confidence interval).", | |
| "statement_location": "Table 4, Economic Policy Model 1a, Log count of parties in system.", | |
| "study_type": "Observational" | |
| }, | |
| "data": { | |
| "source": "Comparative manifesto project (CMP) - the data was published in Ian Budge, Hans-Dieter Klingemann, Andrea Volkens, Judith Bara and Eric Tanenbaum, Mapping Policy Preferences: Estimates for Parties, Electors, and Governments 1945–1998 (Oxford: Oxford University Press, 2001).", | |
| "wave_or_subset": "data from 1945 to 1999", | |
| "sample_size": "20", | |
| "unit_of_analysis": "country-election (party system per one election in established parliamentary democracies)", | |
| "access_details": "the CMP data was published so, most likely, it is open access", | |
| "notes": "Parties were included if they gained at least 1% of parliamentary seats in two consecutive elections. Parties were dropped if below 1% in three consecutive elections. Data was pooled across countries to create a shared two-dimensional policy space. The number of parties is measured both by a simple count of parties meeting the 1% seat threshold and by the effective number of parties based on seat shares. Party dispersion is measured as the distance between the two most extreme parties along each policy dimension (how far apart political parties are from each other in terms of their policy positions)." | |
| }, | |
| "method": { | |
| "description": "The study examines how the number of parties in a political system affects party dispersion in a two-dimensional policy space (economic and social dimensions).", | |
| "steps": "1. Select twenty established parliamentary democracies (Australia, Austria, Belgium, Canada, Denmark, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, New Zealand, Portugal, Spain, Sweden, Switzerland, United Kingdom). \n2. Include parties with at least 1% of seats in parliament in two consecutive elections. \n3. Exclude parties below 1% in three consecutive elections. \n4.Compute number of parties. \n4. Define two policy dimensions (economic and social) using specific CMP categories (p. 814., note 37).\n5. Conduct principal components analysis (PCA) to estimate party positions along each dimension. \n6. Calculate party dispersion as the distance between the two most extreme parties on each dimension within each country–election. \n7. Regress dispersion on the log of number of parties, with robust standard errors clustered by country.", | |
| "models": "ordinary least squares regression of log party dispersion on log count of parties and electoral rules", | |
| "outcome_variable": "party dispersion", | |
| "independent_variables": "log of the count of parties in the system, electoral rules (dummy: 1 = single-member district, 0 = proportional)", | |
| "control_variables": "not stated", | |
| "tools_software": "not stated" | |
| }, | |
| "results": { | |
| "summary": "As the number of parties in the system increases, party dispersion increases and the effect is statistically significant (coefficient on log count of parties in system term = 0.39, robust SE clustered by country = 0.14, coefficient falls within a 95% confidence interval).", | |
| "numerical_results": [ | |
| { | |
| "outcome_name": "Economic policy", | |
| "value": "0.39", | |
| "unit": "NA", | |
| "effect_size": "not stated", | |
| "confidence_interval": { | |
| "lower": "not stated", | |
| "upper": "not stated", | |
| "level": "95%" | |
| }, | |
| "p_value": "not stated explicitly; a 95% confidence interval indicates statistical significance.", | |
| "statistical_significance": "true", | |
| "direction": "positive" | |
| } | |
| ] | |
| }, | |
| "metadata": { | |
| "original_paper_id": "10.1017/S0007123409990172", | |
| "original_paper_title": "The Spatial Structure of Party Competition: Party Dispersion within a Finite Policy Space.", | |
| "original_paper_code": "not stated", | |
| "original_paper_data": "not stated" | |
| } | |
| } | |
| } | |