If a control group doesn’t exist, then there is nothing to compare the experiment to. Without the control group we couldn’t conclude whether the independent variable had an effect on the dependent variable. Subjects should be assigned to certain conditions by using the random assignment method. This means that the participants in both groups have similar characteristics such as age, driving history, gender and education. Thus eliminating preexisting differences in both groups.
9. In not rejecting the null hypothesis, we are actually saying that our sample data does not allow us to reject the null hypothesis. Thus, the null hypothesis is true. 10. If we do not reject the null hypothesis based on sample evidence, we have proven beyond doubt that the null hypothesis is true.
b. potential independent variables that are held constant. c. measured by the researcher. d. probable behavioral causes. 6. One reason a valid experiment may produce null results is a. the range of levels in the independent variable was insufficient to show an effect.
b Operations Experiment 9A: Lab Operations and Uncertainty Jenaqua Hairston Dr. Bump 10/20/11 Purpose/Background During experiments values are obtained and compared to true values which leads to the accuracy of an experiment. However, a complete accurate value is never achieved, because all experimental data is impacted by errors of some sort. Whether it be human error or things along the line of measurements taken, values will not always meet the expectations of a true value. Experimental uncertainty is often present in the form of systematic errors which can not be avoided. Systematic error in physical sciences commonly occurs with the measuring instrument having a zero error.
And according to our data, our actual yield is 0.5g CaCO3. Thus, our percent yield is 73.5%. Our percent yield was close to 100%, but not very close. I believe the error lies in human error, as well as instrumentation sensitivity. Our scale only measures to grams accurately, and could have not accurately represented the .68g of CaCO3, or we could have lost the solid precipitate in the process of the experiment.
Rational knowledge is often derived from syllogisms. Unless both the major and minor premises of syllogisms are sound, the logical conclusions drawn from the rational thoughts are unsound. Scientists cannot rely on rational knowledge alone because rational knowledge involved only form and not content (Jackson, 2009). Empirical knowledge is gained through objective observations and a person’s experience in relation to his or her senses (Jackson, 2009). A person who relies on empirical knowledge only believes what can be detected by his/her senses (sight, sound, taste, etc.).
Society is very complex and in practice it would be impossible to control variables that may influence a situation. Therefore although the ability to control variables in laboratory conditions may be seen as a positive/ advantageous, it on the other hand produces a completely artificial environment which would likely never take place in reality. In this sense field experiments would be a better experimental method as favoured by
In reality, it is very unlikely that the above criteria are all met in a population, but the Hardy-Weinberg equilibrium is still useful as it functions as a null hypothesis. If the expected frequencies of the genotypes differ from that predicted from the Hardy-Weinberg equilibrium significantly, we could conclude that some aspects in the assumptions of the equilibrium are not fulfilled. In a wild population, there usually exists natural selection and this is the main driving force of changing allele and genotype frequencies. For natural selection to occur, there must exist differential fitness between genotypes, i.e. individuals with different genotypes have different chances of survival.
Unlike in a field experiment where the participants are completely unaware that they are being observed so it gives more of a natural response, this allows the researchers to gain results with greater validity. In a laboratory experiment, the researchers have to tell the percipients the reasons for the experiment to allow the percipients to give full consent this is due to the ethical reasons such as if the person doesn’t agree due to religion/beliefs, ethnicity ect. Where as, the percipients of a field experiment have to be unaware of the reasons for the research to allow a higher rate of natural answers. This means that field experiments are less ethically agreed with. An example of a laboratory experiment is Asch (a psychologist) who tested the rate of conformity within groups.