Effect of Intensive Hand Washing Education on Hand Washing Behaviors in Thai Households with an Influenza-Positive Child in Urban Thailand

Abstract

This study assessed the effect of intensive education on self-reported frequency of hand washing (FHW), measured quality of hand washing (QHW), and measured scores of knowledge, attitude, and practice (KAP) after 7 days and 90 days home-based intensive education of participants (aged >7 years) in households with a influenza-positive child. The authors provided intensive hand washing education using interactive participation including individual training, self-monitoring diary, provision of soap, and so on. There were significant improvements on FHW and QHW on day 7, control group (n₁ = 135) reported 3.9 hand washing episodes/day, whereas the intervention group (n₂ = 140) reported 5.7 episodes/day; control group (n₁ = 164) obtained a 3.2 measured quality score, whereas the intervention group (n₂ = 166) obtained a score of 6.4. Pre-education and 90 days post-education, FHW significantly improved by 2 episodes/day and QHW increased by 3 scores/episode. Knowledge of influenza and hand washing following coughing/sneezing showed significant improvement, but attitude modification toward severity of influenza requires a more intensified and longer intervention.

Keywords

hand washing knowledge attitude practice education households influenza Thailand

Introduction

The health and socioeconomic impact of influenza worldwide is substantial and underscores the importance of improving influenza control measures.^1,2 In Thailand, influenza illness significantly affects household economics, mainly from lost work, lost school, and out-of-pocket costs. In 2004, the average total individual cost per influenza illness episode was 663 baht (US$15.78) or approximately 20% of an average monthly Thai income. Influenza illness resulted in an average lost of 3 working days for adults, while parents of infected children missed an average of 4 working days because of caretaking responsibilities.^3,4

Hand washing is a primary preventive strategy to reduce lower respiratory infections and diarrhea and lessen the impact of illness. A study in Pakistan demonstrated that hand washing reduced incidence of pneumonia by 50% and diarrhea by 53% through the facilitation of community-based hand washing education.⁵ Similarly, an intensive hand hygiene program, including hand washing, in Thai schools supported the benefit in reducing influenza-like illness in 60.8% after the first year of promotion.⁶ A school-based hand washing promotion in China also confirmed the advantages of school absenteeism reduction by 3 days.⁷ Consequently, the World Health Organization, US Centers for Disease Control and Prevention, and Thailand Ministry of Public Health have directed individuals in hand washing promotion to lessen the burden of influenza pandemic.^8-10

The evaluation of health education on individual’s behaviors remains an essential aspect of primary care in Thailand.¹¹ However, limited studies illustrated the effect of education on behavior change, in particular the frequency and quality of hand washing before determining the effect of hand washing on the rate of illness. The success of home-based intensive education in modifying behaviors could improve public hand washing campaigns. Therefore, this study examined the effect of home-based intensive hand washing education on self-reported frequency of hand washing (FHW) and measured quality of hand washing (QHW), as well as the change of score on instruments designed to measure knowledge, attitude, and practice (KAP) of hand washing relevant to influenza. These data are needed to support individual hand washing behaviors and assist in the development of hand washing education in Thai households.

Methods

The study was conducted as a component of the Household Influenza Transmission Study (HITS), a household randomized controlled trial of interventions to reduce influenza transmission in Bangkok and metropolitan areas. HITS prospectively identified a confirmed influenza pediatric patients and their households in the outpatient department at the Queen Sirikit National Institute of Child Health (QSNICH) and used block randomization to allocate study groups. This study selected the control group and hand washing group enrolled in HITS based on the purpose of comparing hand washing behaviors between groups that received intensive hand washing education and another group that did not. The study participants were household members aged older than 7 years living with a confirmed influenza-positive child in the household. All household members provided with a written consent to participate and proxy written consent from parents or guardians for children. The educational interventions according to the study groups were provided to all family members during the period April 2008 to May 2009. The behavior data on FHW and KAP were collected during April to October 2008 and QHW data were collected during January to July 2009. The necessary sample size was estimated at 120 to 133 household in each groups based on 80% power to detect the difference between intervention and control household members with 5% type I error. The intervention was assumed to increase FHW and QHW practice by 30%, and we allowed a 10% dropout rate following randomization.

The component of intensive hand washing education was composed of 5 approaches: discussion, individual hand washing training, self-monitoring diary, provision of soap, and provision of written materials. The intervention household members received a 30-minute intensive hand washing education on influenza infection, potential impacts, for example, school and work absenteeism and income loss while caring for an influenza-infected child, the benefits of hand washing and individual training on hand washing technique on day 0/1. The study staff repeatedly provided individual training on hand washing technique and conveyed memorizing messages about “why to wash,” “when to wash,” “how to wash,” and “how hand washing is linked to influenza transmission” during the subsequent home visits on day 3 and 7. Additionally, intervention household members were asked to record frequency of hand washing daily (self-monitoring diary) and received hand washing supplies (liquid plain soap and dispenser) for the 90-day period, as well as written materials that included pamphlets and posters on hand washing technique that was attached near washing sinks in the households. The control household members received a 30-minute routine health education on influenza infection, nutrition, physical activity, and smoking cessation on the first home visit (day 0/1) after randomization.

The FHW was compared using self-reporting. The participants were asked on their average episode of hand washing with soap for at least 20 seconds per day during the study period. Measured QWH was measured by observation using a checklist of hand washing technique. The contents of the check list to assess the QHW and the perfect technique of hand washing was validated by public health experts. The consensus of 5 experts suggested that the perfect hand washing techniques included 4 practices; the use of soap, the technique of rubbing areas of the hand, duration, and method of drying and subsequently assigning the perfect hand washing technique a score of 8.5 points. The use of soap was given a score of 1. The hand was divided into 7 parts: palms, back of hands, fingers, finger interlaced, finger tips, thumb, and wrist. If the 7 areas were rubbed, then a total 5.5 score was given. The duration of rubbing hands >20 seconds was given a score of 1 and the use of clean towel or paper to dry the hands was also given a score of 1. The study staff asked participants in both group to demonstrate their hand washing technique on day 7 in order to compare the difference between groups, and they also asked intervention group to demonstrate their hand washing technique on day 1 (pre-education) and again on day 90, to compare the difference between pre-education and 90 days post-education. Additionally, hand washing techniques on those 4 practices between preintervention and 90 days postintervention were also compared.

The pre–post test of KAP using a 15-question rating scale was obtained for the intervention group on day 1 (pre-education) and day 90 (post-education). The KAP questionnaire was developed and the contents were reviewed by 5 public health experts for validation and the reliability were tested with 31 nonstudy participants. The content validity with regards to item-objective congruence index (IOC) of knowledge was 0.93, of attitude was 0.86, and of practice was 0.93. The reliability coefficient of knowledge (Kuder–Richardson 20) and reliability coefficients (Conbrach’s α) of attitude and practice were <.50.

The knowledge questionnaire contained 5 questions designed to assess the knowledge on influenza and prevention. A score of 1 was given for a correct response. The response of “no” and “don’t know” was classified as an incorrect response and received a “0” score. The attitude questionnaire comprised of 5 questions and responses were measured on a rating scales ranging from 1 to 4 with 1 = strongly disagree, 2 = disagree, 3 = agree, and 4 = strongly agree. The higher score on the scale of ≥3 scores indicated a greater positive attitude toward those statements. The practice questionnaire contained 5 questions and responses were measured on a rating scale ranging from 1 to 5 with 1 = none of the time, 2 = 25% of the action, 3 = 50% of the action, 4 = most of the time, and 5 = always. The higher practice scale of >50% of action indicated that participants were more likely to practice with reference to those practices.

Statistical Analysis

SPSS version 17 was used in the analysis. Individual characteristics between 2 groups were compared using χ² and unpaired t test. The mean of FHW and the mean score of QHW were compared using t test. Hand washing techniques between pre-education and post-education were compared using McNemar test. The percentages of correct responses on knowledge questions (K) between pre-education and 90 days post-education were compared using the McNemar test. The median score on attitude (A) and practice (P) questions between pre-education and 90 days post-education were compared using the Wilcoxon signed rank test. The level of significance for any statistical test was established at α = .05.

Results

Of 226 households, 96 (42%) earned an income of 10 001 to 20 000 Thai-baht/month (~US$312 to US$625) and 45 (20%) households earned >30 000 Thai-baht/month (~US$938). The mean number of household members was 4.4 (SD 1.7; median 4; quartiles 3, 5). A hand washing station defined as a sink with a running water tap and available soap/detergent station was found to range from 1 to 6, with an average of 3 stations per household.

During April to October 2008, 275 household members who met the criteria were selected for determining hand washing behaviors on FHW and KAP; 135 participants were in control group and 140 participants were in intervention group. The majority of participants 234 (85%) were aged 16 to 60 years, and mean age was 34.2 years (SD = 13.3), averaged 11 years of education (SD = 6.7), and 160 (57.3%) were female. Age, gender, and education between control and intervention groups were not statistically different (P > .05; Table 1).

Table 1.

Household Members’ Characteristics in Each Group of Frequency and Quality of Hand Washing Assessments

	Frequency Assessment (n = 275)				Quality Assessment (n = 330)
Characteristics	Control (n₁ = 135)	Hand Washing (n₂ = 140)	Total	P	Control (n₁ = 166)	Hand Washing (n₂ = 164)	Total	P
Age in years; mean (SD)	34.7 (13.6)	33.8 (13.1)	34.2 (13.3)	.56a	34.8 (14.9)	35.7 (13.5)	35.3 (14.3)	.17^a
Education in years; mean (SD)	10.3 (6.4)	11.7 (7.0)	11 (6.7)	.10^a	10.4 (7.0)	10.1 (5.6)	10.3 (6.4)	.62^a
Gender				.80^b				.99^b
Male, n (%)	57 (42.2)	60 (42.8)	117 (42.5)		69 (41.6)	68 (41.5)	137 (41.5)
Female, n (%)	78 (57.7)	80 (57.1)	158 (57.4)		97 (58.4)	96 (58.5)	193 (58.5)

Independent t test.

χ² test.

During January to July 2009, 330 household members were assessed on QHW, 166 participants were in the control group whereas 164 participants were in the intervention group. The majority of participants 265 (80%) were aged 16 to 60 years, mean age was 35.3 years (SD = 14.3), averaged 10.3 years of education (SD = 6.4), and 193 (58.5%) were female. Age, gender, and education between these 2 groups were not statistically different (P > .05; Table 1).

On day 7, the control group (n₁ = 135) reported 3.9 hand washing episodes/day, whereas the intervention group (n₂ = 140) reported 5.7 hand washing episodes/day (P < .001; Table 2). The control group (n₁ = 164) obtained a 3.2 quality score, while the intervention group (n₂ = 166) obtained a 6.4 quality score (P < .001; Table 3).

Table 2.

Effect of Intensive Hand Washing Education on Self-Reported Frequency at 7 and 90 Days Postintervention

	Self-Reported Frequency at 7 Days Postintervention (n = 275)						Self-Reported Frequency at 90 Days Postintervention (n = 133)
	n	Min-Max	Mean (SD)	Mean Difference (95% CI)	P		Min-Max	Mean (SD)	Mean Difference (95% CI)	P
Control	135	0-12	3.9 (2.4)	—	—		—	—	—	—
Intervention	140	2-19	5.7 (3.4)	—	—	Preintervention	0-20	4.1 (2.7)	—
						90 days postintervention	1-22	5.6 (3.5)	—
Total	275	—	—	−−1.7 (−−2.4, −−1.0)	<.001^a	Total	—	—	−1.5 (−2.2, −0.9)	<.001^b

Independent t test.

Paired t test.

Table 3.

Effect of Intensive Hand Washing Education on Measured Quality of Hand Washing at 7 and 90 Days Postintervention

	Measured Quality Score at 7 Days Postintervention (n = 330)						Measured Quality at 90 Days Postintervention (n = 158)
	n	Min-Max	Mea (SD)	Mean Difference (95% CI)	P		Min-Max	Mea (SD)	Mean Difference (95% CI)	P
Control	166	1.5-8	3.2 (1.2)	—	—		—	—	—	—
Intervention	164	2.5-8.5	6.4 (1.7)	—	—	Preintervention	1.5-8	3.2 (1.3)	—	—
						90 days postintervention	2-8.5	6.5 (1.8)	—	—
Total	84	—	—	−3.1 (−3.4, −2.8)	<.001^a	Total	—	—	−3.3 (−3.7, −2.9)	<.001^b

Independent t test.

Paired t test.

In comparison to hand washing practices of pre-education and 90 days post-education in the intervention group, the frequency increased from 4.1 (SD = 2.7) to 5.6 (SD = 3.5) and quality score improved from 3.2 (SD = 1.3) to 6.5 (SD = 1.8). In addition, hand washing techniques on the 4 practices showed significant improvement. The percentage of participants who used soap increased from 33.5 to 88.0 (P < .001); the percentage of participants using clean towel/paper for drying hands increased from 69.0 to 94.3 (P < .001); the percentage of participants who cleaned all areas of their hands increased from 0.9 to 39.4 (P < .001), and the duration of washing hands increased from 25.9 to 59.2 seconds (P < .001; Table 4).

Table 4.

Effect of Hand Washing Education on Observed Hand Washing Technique (n = 158)

Hand Washing Practices	Preintervention	90 Days Postintervention	P
Used soap; n (%)	53 (33.5)	139 (88)	.001^a
Used clean towel or paper; n (%)	109 (69)	149 (94.3)	.001^a
Cleaned all area of hands; n (%)	3 (0.9)	130 (39.4)	.001^a
Duration of hand washing in seconds; mean (SD)	25.9 (15.5)	59.2 (25.0)	<.001^b

McNemar test (binomial distribution used).

Paired t test.

The percentage of participants who gave correct responses on the 5 knowledge questions between pre- and postintervention significantly increased (P < .001). There were no significant differences between the pre and post median scores of attitude questions toward severity of influenza. However, the pre and post median scores of attitude question toward “Hand washing is a good way to protect my family from influenza infection” did improve (P = .004). The pre and post median scores on hand washing in relation to preventing respiratory infection were statistically different. Participants reported washing their hands more frequently after using their hands to cover their mouth and nose when coughing, sneezing, or blowing their nose (P = .001) and after touching or handling presumed secretion-contaminated surfaces such as books, door knobs, and telephone (P < .001). They also reported that they washed their hands with soap more often (P = .005; Table 5).

Table 5.

Effect of Hand Washing Education on Knowledge, Attitude, and Practice Between Preintervantion and 90 Days Postintervention (n = 127)

Questions	Preintervention	90 Days Postintervention	P
Knowledge: n (% of corrected response)
1. Influenza infection is caused by a change in the weather	3 (2.3)	17 (13.4)	<.001^a
2. I am more likely to catch influenza when I am very near (1 meter or less) to a person with influenza	70 (55.1)	108 (85.0)	<.001^a
3. The best way to reduce influenza transmission in my household is to cover my mouth and nose when I sneeze or cough, to wash my hands, and to clean surfaces such as door knobs, books, etc	100 (78.7)	120 (94.5)	<.001^a
4. Washing my hands several times each day helps protect my family from infection	104 (81.9)	123 (96.9)	<.001^a
5. Washing my hands for 20 seconds or longer with soap and running water can remove the influenza virus from my hands	73 (57.5)	110 (86.6)	<.001^a
Attitude: Median (interquartile range)
1. Severity: Influenza can cause me to miss school or work	3 (3, 4)	3 (3, 4)	.31^b
2. Severity: Influenza infection can cause young children and elderly to be admitted to hospital	3 (2, 3)	3 (2, 3)	.35^b
3. Severity: Influenza infection is serious enough that I should take steps to prevent it	3 (3, 4)	3 (3, 4)	.10^b
4. Preventive behaviors: Taking vitamins, sleeping at least 8 hours each night, and getting daily exercise will help protect me from getting influenza	3 (3, 3)	3 (3, 4)	.18^b
5. Hand washing: Hand washing is a good way to protect my family from influenza infection	3 (3, 4)	3 (3, 4)	.004^b
Practice: Median (interquartile range)
1. Social distancing: When I get influenza, I stay home from school, work, and social gatherings to protect others from catching my influenza	3 (2, 4)	3 (2, 4)	.82^b
2. Cough etiquette: I cover my mouth and nose with a tissue when I cough or sneeze	3 (3, 5)	4 (3, 4)	.17^b
3. Hand washing: I wash my hands after covering my mouth and nose when I cough or sneeze or blow my nose	3 (3, 4)	4 (3, 5)	.001^b
4. Hand washing: I wash my hands after I touch any object that I know has been touched by a person in my household who has a cough or runny nose	3 (2, 3)	4 (3, 4)	<.001^b
5. Hand washing: I wash my hands with soap and water	3.5 (3, 5)	4 (3, 5)	.005^b

McNemar test, each item was binomial distribution.

Wilcoxon signed rank test.

Discussion

Intensive hand washing education significantly increased self-reported frequency by 2 episodes per day, the quality of hand washing by 3 scores and improved hand washing technique. Additionally, the educational intervention significantly increased knowledge on influenza and improved practices in relation to preventing influenza transmission.

These improvements were facilitated by the strengths of educational approaches. First, the repeated information on influenza and in memorizing messages of good hand washing practices helped create an awareness of susceptibility to acquire influenza and its consequence that ultimately encouraged good hand washing practice. Second, the provision of hand washing supplies helped minimize environmental barrier. This component was strongly suggested by the guidance of hand washing promotion and previous hand washing study to strengthen the intention to routinely wash the hands.^12,13 Third, the incorporation of a self-monitoring diary provided subjects an opportunity to actively participate in the process of self-reminder and self-control, a widely used strategy in changing certain health-related behaviors, for example, eating and exercising.^14,15 This component likely played a role in supporting the success on increasing the frequency of hand washing among our study participants. Fourth, individual training, including one-on-one demonstration, assisted the improvement of hand washing technique that reflected the quality of hand washing practices. This approach is acknowledged as the most efficient way to visualize hand washing technique and an opportunity for the health educators to explain the reasoning, offer immediate feedback and correction, and reinforce the benefits of proper hand washing technique.¹⁶ Last, this study was conducted under the context of a household randomized controlled trial that could reduce selection bias and confounders, for example, age, gender, education that were comparable in both groups.

Even though the educational intervention significantly improved knowledge and self-reported hand washing practices consistent with a study in India,¹⁷ these educational approaches with 90-day duration of intervention did not support the change on the attitude toward severity of influenza, perhaps because of insufficient time. Theoretically, an educational program would require an intensified approaches and longer intervention of more than 1 year to achieve positive attitude changes.^18-20

This study had several limitations. First, the increased frequency of hand washing was based exclusively on self-reporting, with a tendency of overreporting. Similar studies have showed a tendency for participants to overreport.^21,22 Because of limited resources in the context of the ongoing project, it was not possible to include more intensive observational methods. However, evaluation methods such as designated household member to monitor hand washing behavior, measuring individual hand washing soap use, and spot checking of the hand washing facilities could reduce bias. Second, the observed quality of hand washing practices used in this study was based on an instrument that was developed specifically for this study and was not subjected to extensive validation testing. Observation bias (Hawthorne effect) may have resulted in increased hand washing, more than the actual practices because participants were aware of being observed by the study staff.^23,24 Thus, the quality of hand washing measurements needs further investigation. Finally, the questionnaire on knowledge, attitude, and practice of individuals was developed to assess the effect of hand washing education using specific approaches that meet the needs of Thai households with an influenza-infected child and may not be generalizable to other populations. The standardized questionnaire that was developed, refined, validated, and tested for its reliability and item analysis is suggested for future use.

Conclusion

The home-based intensive hand washing education repeatedly conveyed consistent messages on hand washing, individual training, provision of hand washing supplies, and use of a self-monitoring diary, improved hand washing behaviors on frequency, technique, and knowledge. Attitudes toward the severity of influenza did not change. This finding reaffirm that the educational intervention should be extended and aimed at modifying attitudes in relation to respiratory infections and the severity of influenza. In conclusion, sustainable hand washing behavior needs to be evaluated in a long-term follow up program (>1 year).

Footnotes

Acknowledgements

The authors extend appreciation to the Household Influenza Transmission Study (HITS) staff for their participation, time and contribution in conducting the educational intervention.

Declaration of Conflicting Interests

The author(s) declared no conflicts of interest with respect to the authorship and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research and/or authorship of this article:

This study was funded by The 90th Anniversary of Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund). The larger Household Influenza Transmission Study (HITS) study was funded by the US Centers for Disease Control and Prevention.

References

Viboud

Boëlle

Cauchemez

. Risk factors of influenza transmission in households. Br J Gen Pract. 2004;54:684-689.

Principi

Esposito

Gasparini

Marchisio

Crovari

. Burden of influenza in healthy children and their households. Arch Dis Child. 2004;89:1002-1007.

Clague

Chamany

Burapat

. A household survey to assess the burden of influenza in rural Thailand. Southeast Asian J Trop Med Public Health. 2006;37:488-493.

Simmerman

Thawatsupha

Kingnate

Fukuda

Chaising

Dowell

. Influenza in Thailand: a case study for middle income countries. Vaccine. 2004;23:182-187.

Luby

Agboatwalla

Feikin

. Effect of handwashing on child health: a randomised controlled trial. Lancet. 2005;366:225-233.

Apisarnthanarak

Cheevakumjorn

Mundy

. Intervention with an infection control bundle to reduce transmission of influenza-like illnesses in a Thai preschool. Infect Control Hosp Epidemiol. 2009;30:817-822.

Bowen

. A cluster-randomized controlled trial evaluating the effect of a handwashing-promotion program in Chinese primary schools. Am J Trop Med Hyg. 2007;76:1166-1173.

World Health Organization. WHO Guidelines on Hand Hygiene in Health Care (advanced draft). http://www.who.int/patientsafety/information_centre/ghhad_download_link/en/ . Accessed July 20, 2006.

Centers for Disease Control and Prevention. CDC Says “Take 3” Actions to Fight the Flu. http://www.cdc.gov/flu/protect/preventing.htm . Accessed November 25, 2009.

10.

Thailand Ministry of Public Health. Public Health Advice No.1-8 Pandemic H1N1 2009. http://www.mfa.go.th/web/2933.php?page=1 . Accessed on November 25, 2009.

11.

Kitreerawutiwong

Kuruchittham

Somrongthong

Pongsupap

. Seven attributes of primary care in Thailand. Asia Pac J Public Health. 2009;22:289-298.

12.

Luby

Halder

. Associations among handwashing indicators, wealth, and symptoms of childhood respiratory illness in urban Bangladesh. Trop Med Int Health. 2008;13:835-844.

13.

Curtis

Cardosi

Scott

. The Handwashing Handbook: A guide for Developing a Hygiene Promotion to Increase Handwashing With Soap. 2000. http://siteresources.worldbank.org/INTWSS/Publications/20389151/HandwashingHandbook.pdf . Accessed July 20, 2009.

14.

Boutelle

Kirschenbaum

Baker

Mitchell

. How can obese weight controllers minimize weight gain during the high risk holiday season? By self-monitoring very consistently. Health Psychol. 1999;18:364-368.

15.

Levy

Finch

Crowell

Talley

Jeffery

. Behavioral intervention for the treatment of obesity: Strategies and effectiveness data. Am J Gastroenterol. 2007;102:2314-2321.

16.

Newby

Stepich

Lehman

Russell

. Instructional Technology for Technology and Learning: Introduction to Instructional Technology for Teaching and Learning. Englewood Cliffs, NJ: Educational Technology Publications; 1996:48.

17.

Malhotra

Lal

Prakash

Daga

Kishore

. Evaluation of a health education intervention on knowledge and attitudes of food handlers working in a medical college in Delhi, India. Asia Pac J Public Health. 2008;20:277-286.

18.

Ajzen

. The Theory of Planned Behavior: Organizational Behavior and Human Decision Processes. 1991. http://www.courses.umass.edu/psyc661/pdf/tpb.obhdp.pdf . Accessed March 13, 2010.

19.

Glanz

Rimer

Lewis

, eds. Models of individual health behavior. Health Behavior and Health Education: Theory, Research and Practice. 3rd ed. San Francisco, CA: Jossey-Bass; 2002:41-159.

20.

Strecher

DeVellis

Becker

Rosenstock

. The role of self-efficacy in achieving health behavior change. Health Educ Q. 1986;13:73-92.

21.

Haas

Larson

. Measurement of compliance with hand hygiene. J Hosp Infect. 2007;66:6-14.

22.

Moret

Tequi

Lombrail

. Should self-assessment methods be used to measure compliance with handwashing recommendations? A study carried out in a French university hospital. Am J Infect Control. 2004;32:384-390.

23.

Jones

. Was there a Hawthorne effect? Am J Sociol. 1992;98:451-468.

24.

Wickstrom

Bendix

. The “Hawthorne effect”—what did the original Hawthorne studies actually show? Scand J Work Environ Health. 2000;26:363-367.