answer the following questions about possible research options. Create a researc
ID: 3217654 • Letter: A
Question
answer the following questions about possible research options. Create a research question in the field of psychology that you are interested in researching. Write questions clearly. Include a brief background of the problem you are proposing and why it is important to the field of psychology. State the null and alternative hypothesis (in both words and statistical notation) need to address the research question. Choose which statistical test would be used to conduct the study and support it with research. Describe the type of data needs to be collected to conduct the study and what techniques are best for collecting data.
Explanation / Answer
Hypothesis testing –
Hypothesis testing is an inferential procedure that uses sample data to evaluate the credibility of a hypothesis about a population.
The null hypothesis (H0) predicts that the independent variable (treatment) has no effect on the dependent variable for the population.
The alternative hypothesis (H1) predicts that the independent variable will have an effect on the dependent variable for the population - we'll talk more about how specific this hypothesis may be
Experimenter's Conclusions
H0 is correct
H0 is wrong
Reject H0
Fail to reject H0
oops!
Type I error
Yay!
correct
Yay!
correct
oops!
Type II error
The two kinds of error each have their own name, because they really are reflecting different things
type I error (a, alpha) : the H0 is actually correct, but the experimenter rejected it
- e.g., there really is only one population, even though the probability of getting a sample was really small, you just got one of those rare samples
type II error (b, beta) : the H0 is really wrong, but the experiment didn't feel as though they could reject it
- e.g., your sample really does come from another population, but your sample mean is too close to the original population mean that you aren't can't rule out the possibility that there is only one population
step1: Make a hypothesis and select a criteria for the decision
Your hypothesis is an educated guess/prediction about the effect of particular events/treatments/factors (which result in differences between populations). your hypothesis may be general (e.g., this course will change comprehension abilities), or specific (e.g., this course will improve comprehension abilities by at least 10%).
step2: Collect a sample
Randomly select individuals from a population, randomly assign selected individuals to specific treatment groups
(note that in our example above we didn't do this, we assigned individuals to groups based on their past experiences. As a results our conclusions could be compromised, maybe the people who take stats are generally people who have better comprehension abilities, and so taking stats didn't have anything to do with their performance on the test)
after the treatment, the question that we have is roughly, are all of our individuals in the same population, or do we have individuals belonging to a new population because of our treatment
step3: Compute a test statistic (more on this later in the lecture, and the course)
things like z-scores, t-tests, f-tests (ANOVA)
step4: Compare the test statistic to a distribution to make an inference about the parameter and hence draw a conclusion about the sample.
roughly, how likely is this difference due to sampling error? Given this probability, what should we conclude?
Make a hypothesis and select a criteria for the decision The standard logic that underlies hypothesis testing is that there are always (at least) two hypotheses: the null hypothesis and the alternative hypothesis.
The logic of hypothesis testing assumes that we are trying to reject the null hypothesis, not that we are trying to prove the alternative hypothesis
Why?
Generally, It is easier to show that something isn't true, than to prove that it is. This is especially true when we are dealing with samples. Remember that we aren't testing every individual in the population, only a sub set.
Hypothesis Example : All dogs have 4 legs.
to reject: need to have a sample which includes 1 or more dogs with more or fewer than 4 legs. to accept: need to examine every dog in the population and count their legs
So part of the first step is to set up your null hypothesis and your alternative hypothesis
The other part of this step is to decide what criteria that you are going to use to either reject or fail to reject (not accept) the null hypothesis
So consider the problem that we have. We have a sample and its descriptive statistics are different from the population's parameters (which may be based on the control group sample statistics). How do we decide whether the difference that we see is due to a "real" difference (which reflects a difference between two populations) or is due to sampling error?
To deal with this problem the researcher must set a criteria in advance.
Psychology is based on the scientific method and involves:
The researcher chooses the research method that will better address the research topic. Psychologists rely on three basic types of research methods to perform their studies of behaviours and mental processes: descriptive, co relational, and experimental. Descriptive methods involve systematic observations and recording of behaviours.
The four types of descriptive methods discussed are Observations, Surveys and Interviews, standardized tests, and case studies.
Observations can take placed in natural settings or in laboratories. In naturalistic observation, the psychologist observes behaviour in real-world settings and makes no attempt to manipulate or control the situation. However, many of the observations that take place in psychology occur in the laboratory, which gives the psychologist control over factors; for this reason, there are several drawbacks to this method, such as the unnatural behaviors that result from people knowing that they are being observed.
An interview involves asking people questions to find out about their experiences and attitudes. One problem of interviewing people is the concern of participants to tell the interviewer what they think is socially acceptable or desirable.
Surveys or questionnaires require subjects to read questions and mark their answers. Some psychologists observe behavior and mental processes by administering standardized tests.
Standardized tests allow the researcher to measure some aspect of the participant's behaviors and/or mental processes, and compare each individual's outcome to others that have also performed the same test.
The case study, which provides an in-depth examination of a single individual, from which the results may not be easily generalized to other people.
In order to analyze the data collected in systematic research, psychologists rely on statistics. There are two basic categories of statistics: Descriptive and Inferential.
Descriptive statistics are used to summarize the information acquired in the study. Two types of descriptive statistics are discussed : (1) measures of central tendency, which are used to assess the general tendencies or the "average" behaviour or mental process that was observed in the study, and (2) measures of variability, which inform us as to the differences in behaviours and mental processes inside the sample that was studied. Once you understand the three most common types of measures of central tendency, you will understand the importance of measures of variability. The first measure of central tendency is the mean. This is what we commonly associate with an "average" response.
The mean is calculated by adding all the scores and then dividing that total by the number of scores or participants.
The median is the score that stands right in the middle of the series of scores.
The third measure of central tendency is the mode, which is the most typical score in the series of scores; . in other words, the most typical behaviour observed in the study. While these three measures of central tendency do give us a summary or idea of the behaviours and mental processes observed in the participants of the study, they do not include information about the individuals in the study and the differences between the participants. Here is where the measures of variability play a very important role in psychological research.
The range and the standard deviation give information about the differences between the people that participated in the study. The range is the distance between the highest and the lowest score.
The standard deviation is a measure of on average, how different individuals are from the mean or average behaviour. The higher the standard deviation, the more difference was there between the mean score and the scores of individuals. In other words, the higher the standard deviation, the less descriptive or representative is the mean of the behaviours and mental processes of the individual participants.
Inferential statistics are used to analyze the data collected in the study to test the hypotheses that guided the study.
A hypothesis explains the expected relationship between the manipulated independent variable and the dependent variable. Inferential statistics inform the researcher regarding the extent to which the relationship between the independent variable and the dependent variable is real and significant or is due to chance.
Psychologists only report an effect as significant if the inferential statistics indicate that the odds of the results being due to chance is equal or less than 5 out 100 or .05 statistical significance.
H0 is correct
H0 is wrong
Reject H0
Fail to reject H0
oops!
Type I error
Yay!
correct
Yay!
correct
oops!
Type II error
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