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pdf - Nyenrode Business Universiteit

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5.3. LIMITATIONS AND SUGGESTIONS FOR FURTHER RESEARCH 127<br />

5.3.2 Causality<br />

The second limitation arises from the fact that I use cross-sectional data for my analyses,<br />

which measure the independent and dependent variables at one point in time. Although<br />

this type of quantitative research has several benefits (e.g., relatively large-scale datasets,<br />

which increases the generalizability of the results), the method has drawbacks as well.<br />

With this method, I cannot fully test the causal character of the relations. A common trap<br />

in interpreting statistical results is to claim causation when the empirical methodology<br />

supports correlation (Echambadi et al. 2006:1811). I stress here that I theorize causation<br />

but primarily test associations. Research methods that incorporate longitudinal data (e.g.,<br />

longitudinal case studies) are better equipped to determine causality.<br />

Nonetheless, I take steps to detect potential problems with causality. In chapters 3 and<br />

4, I test for the endogeneity of the independent variables. Endogeneity occurs if the<br />

independent variable included in the model is correlated with the error terms of the estimated<br />

model. Sources of endogeneity include reverse causality, simultaneous causality,<br />

and omitted variables. Ignoring endogeneity may lead to biased and inconsistent estimates<br />

(Echambadi et al. 2006:1805). Hausman test results indicate that endogeneity is not a<br />

major concern in my models and that the results from my analyses are not biased by endogeneity.<br />

However, the endogeneity analysis cannot positively rule out reverse causality.<br />

Future research may wish to rely on panel data or design experiments to fully rule out<br />

reverse causality (Echambadi et al. 2006:1805).<br />

5.3.3 Measurement<br />

The final limitation that I discuss here refers to the measurement of my variables. This<br />

thesis relies on an extensive questionnaire. I invested considerable time and effort into<br />

the survey instrument. For example, I conducted several rounds of pretesting among the<br />

potential respondents. Doing so certainly improved the quality of the data that were obtained<br />

for this study. However, with the benefit of hindsight, several measures leave room<br />

for improvement. Most importantly, the RPE proxies that are used in this study can be<br />

improved. I use two different RPE measures that have specific strengths and weaknesses.<br />

Looking back, I should have developed an overall measure to function as a safety net under<br />

the measures that investigate specific manifestations of RPE. If I had developed this overall<br />

RPE measure, I would have invested in the other specific RPE measures such that they<br />

would show less overlap with each other and only overlap with the overall measure.<br />

In addition to the RPE measures, other measures can be improved as well. For example,<br />

the measure for noise in the performance evaluation (i.e., the dependent variable in chapter<br />

3) is less than perfect. I established the noise measure by using a single-item construct.

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