A Primer on Visualizations for Comparing Populations,Including the Issue of Overlapping Confidence Intervals

In comparing a collection of K populations, it is common practice to display in one visualization confidence intervals for the corresponding population parameters θ₁, θ₂, …, θ_K. For a pair of confidence intervals that do (or do not) overlap, viewers of the visualization are cognitively compelled to declare that there is not (or there is) a statistically significant difference between the two corresponding population parameters. It is generally well known that the method of examining overlap of pairs of confidence intervals should not be used for formal hypothesis testing. However, use of a single visualization with overlapping and nonoverlapping confidence intervals leads many to draw such conclusions, despite the best efforts of statisticians toward preventing users from reaching such conclusions. In this article, we summarize some alternative visualizations from the literature that can be used to properly test equality between a pair of population parameters. We recommend that these visualizations be used with caution to avoid incorrect statistical inference. The methods presented require only that we have K sample estimates and their associated standard errors. We also assume that the sample estimators are independent, unbiased, and normally distributed.     

On some properties of variable size simple random sampling and a limit theorem

This paper introduces a sampling plan for finite populations herein called “variable size simple random sampling” and compares properties of estimators based on it with results from the usual fixed size simple random sampling without replacement. Necessary and sufficient conditions (in the spirit of Hajek (1960)) for the limiting distribution of the sample total (or sample mean) to be normal are given.     

Impression management in the market for residential care for children and youth in Sweden

In what has become quite a turbulent quasi‐market for residential care for children and youth, providers now compete for public contracts. To create visibility and attract customers, many providers use marketing activities to project the desired impression of themselves to maintain or strengthen their market position. In this article, we analyse how companies that provide residential care for children manage the impressions they project on their websites and in advertisements. The results reveal that residential care providers use a range of impression management strategies to enhance their organizational image and to respond to potentially damaging or threatening images. The information providers choose to disclose leaves customers—in this case, the social workers responsible for choosing and purchasing care on behalf of clients—with rather limited opportunities to evaluate the quality of care. This is a significant problem considering other, more reliable, sources of information are difficult to access.     

Effects of psychosocial interventions on behavioural problems in youth: A close look at Cochrane and Campbell reviews

Research indicates that a number of psychosocial interventions are effective for reducing behavioural problems in youth. These interventions are now often included on best practice lists aiming to facilitate informed treatment choices among practitioners. However, analyses in neighbouring research areas have highlighted serious shortcomings in how primary studies are analysed and how studies are synthesised in research reviews. This study took a closer look at the evidence of efficacy for psychosocial interventions that aim to reduce behavioural problems in youth, as shown in systematic research reviews by the Cochrane and the Campbell Collaborations (n = 8). The findings suggest a bias towards overemphasising the efficacy of the interventions in several reviews, an over‐confidence in the validity of the findings in some reviews and, overall, a somewhat uncertain evidence base for the efficacy of the interventions. Systematic reviews are crucial for summarising research but more attention to methodological issues may be needed in this area.     

The Influence of Family Structure Vs. Family Climate on Adolescent Well-Being

A study was conducted to explore adolescent well-being as a function of family climate versus family structure. Two hundred seventy-eight adolescents (52% female, 48% male; mean age = 14.78 years) completed questionnaires that assessed family structure (nuclear, single-parent, step), family climate (level of satisfaction with one’s family and level of negative affect in one’s family), and several indicators of current well-being (educational expectations, self-esteem, hopelessness, delinquent attitude scores, and optimism). Participant well-being did not vary by family structure. However, family climate and well-being were significantly related. Implications of the study’s findings are discussed.     

Muslims Opposing Violent Radicalism and Extremism: Strategies of Swedish Sufi Communities

Europe has seen the development of a new research agenda in response to Islamist terror attacks of recent years. Researchers are not only trying to solve the “radicalization puzzle” in order to understand the reasons why young Muslims in Western countries are attracted to extremism, but they are also making proposals for de-radicalizing extremists and creating relationships of trust with Muslim communities. Directly or indirectly, Europe’s Muslim minorities are the objects of the interventions and preventive work under discussion. This study suggests an alternative approach. Rather than regarding Muslims in Europe as more or less passive objects of various anti-extremism interventions, it directs attention toward the strategies developed by European Muslims themselves in fighting Islamist extremism. Using qualitative interviews with leaders of five Sufi communities in Sweden, the study examines a series of strategies for meeting the challenges posed by extremists.     

Perceived contra observed physical work load in Swedish dentists

In an earlier questionnaire study, dentists reported high experienced physical work load in their profession, but low to moderate complaints from their musculoskeletal system. The correlation between reported physical work load and pain from the musculoskeletal system was weak. This discrepancy could not be satisfactorily explained. Therefore, a second study was undertaken, in which the same 27 dentists who reported musculoskeletal problems were video recorded during one hour of clinical work, and the records were later analyzed using PEO (Portable Ergonomic Observation). PEO is a frequency analysis method which allows observation of work in real time using a portable computer or video recordings. PEO can be adjusted for registration of single or multiple work operations. Output data are presented as frequency, duration, and sequence of the various work operations. The aim of the present study was to investigate if there was a relation between observed work load recorded with PEO, and subjectively estimated work load and musculoskeletal complaints recorded with a questionnaire based on Visual Analogue Scales. Sitting and standing postures, and head, trunk and arm movements were analyzed. The PEO observations showed that dentists generally perform their clinical work in a sitting position, with the head bent forward almost half of the time. Only weak to moderate correlations (r =0.0-0.6) were found between observed physical work load and subjective estimations of experienced physical work load and musculoskeletal complaints. These findings support the results in our previous study, but they do not explain the large difference between the observed low work load and the subjectively experienced high work load. The study will be followed up by EMG measurements and free interviews, where both muscular load and psychosocial factors will be evaluated.     

Perceived inflation and expected future prices in different currencies

Five experiments were conducted to investigate whether perceived inflation and expected future prices are influenced by the nominal representation of increases in product prices in different currencies. In contrast to previous research demonstrating overestimates of the perceived inflation of product prices after the transition of the domestic German Mark to Euro [Greitemeyer, T., Schultz-Hardt, S., Traut-Mattausch, E., & Frey, D. (2005). The influence of price trend expectations on price trend perceptions: Why the Euro seems to make life more expensive? Journal of Economic Psychology, 26, 541–548; Traut-Mattausch, E., Schultz-Hardt, S., Greitemeyer, T., & Frey, D. (2004). Expectancy confirmation in spite of disconfirming evidence: The case of price increases due to the introduction of the Euro. European Journal of Social Psychology, 34, 739–760], the price increases were of normal magnitude (5% and 8%) and a larger set of prices was used including small weekly expenses, prices of durables, and rent. All experiments were conducted in Sweden (not member of the European monetary union) employing undergraduates who volunteered to participate in class settings without any financial compensation. The price increases were expressed in the same currency, either actual currencies (Swedish Crowns or Euros) or fictitious currencies with different units. In general inflation was underestimated, to a larger extent when the currency or the product prices were unfamiliar than familiar. It was also shown that product-specific price changes made it difficult to perceive inflationary price increases. Only marginal effects of currency unit were observed.