Social Support vs. Loneliness • Condition Single Married • Suicide 25.8 12.2 • Cirrhosis of liver 8.0 2.1 • Motor vehicle accidents 58.8 35.6 • T.B. 6.9 1.4 • Mean days hospitalized 19.2 9.8 (Mortality/100,000) Loneliness and Health Dr. James Lynch has argued in The broken heart: The medical consequences of loneliness that social isolation leas to loneliness which in turn is the cause of emotional deterioration followed by actual physical deterioration. He cites higher coronary death rates for Irish-Americans residing in Boston compared to those in Ireland (where a more close-knit society is supposed to exist) and a higher death rate in Nevada compared to neighbouring (and presumably more family oriented Mormon Utah. What other explanation for these results might be offered? Speeding and Highway Fatalities After the energy crisis in the U.S., the highway speed limit was lowered to 55 m.p.h. in an effort to conserve gasoline. In 1973 there were 55,000 highway fatalities. In 1974, there was a 20% decrease in such fatalities, with a further 2% in 1975. In 1976, highway fatalities increased, and this increase was attributed to a rise in highway speeds. What other factors might have caused fatalities to have increased during this time period? Deadly Corvettes Recent statistics indicated that the Corvette sports car is the most dangerous vehicle on Canadian highways as measured by driver deaths. This automobile has a fiberglass body and very large, powerful engine which is placed in the front of the vehicle. There is no trunk and the weight distribution is disproportionately in the forward position of the vehicle. May we conclude that the design and construction of the vehicle is responsible for causing driver deaths? Cola Wars The Pepsi-Cola corporation decided to combat the 3:1 sales lead of Coca-Cola in Dallas by commissioning a taste preference study of Texans. Coke drinkers in Dallas were the participants and were asked to indicate their preference for either a sample drink of Coke or Pepsi. Since the testers did not want to label the drinks by brand name, they placed the Coca- Cola in glasses labeled “Q” and the Pepsi-Cola in glasses labeled “M”. The results indicated a 2:1 preference of Coke drinkers for Pepsi. Aside from obvious taste differences, what other factors might have influenced beverage choice? Vs. Consumer’s Reports Bread Nutrition Evaluation The Consumer’s Union decided to test the nutritional value of 33 commercially produced American breads. Rather than evaluate the posted nutritional label required on U.S. food products, they arranged for a consultant to run an animal study. After a one-week period to acclimate the rats to the lab, 36 groups consisting of six rats were established. Three groups constituted the comparison group: one group received lab rat food as a control, one was fed eggs and the other, milk. All groups were provided unlimited quantities of their feed along with water. The rats’ growth rate was studied, along with the condition of the rat’s teeth and coat. Nervousness was measured as were any abnormalities. The results indicated that one group of rats feed a specific brand of bread (Thomas’ Rite Diet Bread) achieved superior health compared to the other groups. Assume that random assignment of all rats to treatment groups. Can you suggest a rival hypothesis? Boating Safety There has been a recent shift in Canada to licence boaters. This concern has developed over the high rate of accidents and fatalities among boaters. Power boaters are disproportionately involved in accidents compared to those in sailboats. May we conclude that power boaters are inherently more dangerous because of their large engines and speed? Why are the less maneuverable sailboats not involved in as many accidents? Vs. The Case of the Dentist’s Drill A survey of dental students at the University of Tennessee found that they suffered a significant loss of hearing within three years of using high speed drills. These instruments reduce a patient’s discomfort, but seem to cause a hearing loss. The researchers in Tennessee recommend that dentists wear hearing protection on the job. What other factors might cause these students to suffer hearing loss? Diffusion of Responsibility in Tipping • In their work on diffusion of responsibility, Latané and Darley examined tipping behaviour of restaurant patrons. They found that solitary dinners were more generous tippers than groups of dinners and concluded that tipping is another example of individuals using the group to avoid performing normative obligations. What alternatives would you suggest? Diffusion of Responsibility in Charitable Donations Wiesenthal, Austrom, and Silverman (1983) established a charity drive for earthquake victims and examined the diffusion of responsibility in charitable donations. A student fundraiser approached other students seated either in groups, or by themselves, in various campus pubs. Solitary individuals were the most generous, while groups (especially larger groups) were noticeably stingier. While the data support the notion of diffusion of responsibility, what other explanations could be posed for these results? Wiesenthal, D. L., Austrom, D., and Silverman, I. (1983). Diffusion of responsibility in charitable donations. Basic and Applied Research in Social Psychology, 4, 17-27. Bumper Stickers and Police Harassment To investigate reports that the California State Police were harassing black motorists in the late 1960s, a social psychologist selected three groups of five students (white, blacks, Chicanos) all of whom had excellent driving records. They were to drive cars that had satisfactorily completed a safety inspection. The cars either had a Black Panther Party bumper sticker or a Support the Police sticker. The Panthers had been in a number of violent confrontations with the police, especially in California. Within 17 days, the drivers with the Black Panther stickers had received 33 citations. The authors claimed that the data supported the notion of police harassment. Are other explanations possible? Types of Validity Internal: are the differences in the dependent variable (measure) due to the operation of the operation of the independent variable and not due to an extraneous (confounding) variable. External (or ecological validity): the extent that the results generalize to the real world Statistical: accuracy of the conclusion from a statistical test Construct: the degree to which the theory(ies) behind the research provides the best explanation for the obtained results. How well do the results support the theories, models, constructs behind the research or/and do they provide the best available theoretical explanation for the results. Types of Validity Discriminant validity: when a measure does not correlate highly with a measure of a different construct. Example: a violence measure might have a degree of discriminant validity if it does not correlate with the measures of assertiveness, social desirability, and independence. Convergent validity: the extent to which your measure correlates with other indicators of the construct. Threats to Statistical Validity • Dependent variable (measure(s)) is (are) unreliable. • Statistical assumptions underlying statistical tests have been violated (example: in t-tests and ANOVAs are the means and variances correlated? Are the distributions approaching normality or are they skewed?). Internal Validity Definition: The results of an experiment being attributable to the operation of the independent variable. It asks whether the obtained differences between the experimental condition or groups are really the result of the experimental manipulations. Threats to Internal Validity • Reactivity • Reliability of measuring instruments/stimulus delivery • Inconsistent treatment administration • Selective subject loss • Experimenter bias • Nonrandom assignment • Contamination of the subject pool • Experimenter effects: active/passive • Subject role-related behaviours • Effects of previous testing (carryover effects) • Omission of a key (control) group I External Validity Definition: To what extent can the present results generalize to other samples, situations, tasks. Quasi-experiments Experiments lacking random assignment of subjects to treatment conditions and the absence of an independent variable manipulated by the experimenter. Example: automobile deindividuation study.