• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Statistical Analysis for IB Psychology. The chi-square test is a method of statistical analysis used for comparison of observed/ actual data to expected data.

Extracts from this document...

Introduction

Chi-Square Test The chi-square test is a method of statistical analysis used for comparison of observed/ actual data to expected data. Chi-squared asks and answers the question, "Does my observed data fit with my expectations?". It is measured as the probability for your event to occur, p> .05 or p<.05. The higher your x2 (chi-square) value, the less likely your results are accurate (or due to chance). The lower the value, the more accurate, or likely to occur. Example: A restaurant owner expects that over the course of 6 days, 10% will come in on Monday, 10% on Tuesday, 15% on Wednesday, 20%on Thursday, 30% on Friday, and 15% on Saturday. This is his 'Expected distribution'. The null hypothesis would be that: H0= The owner's distribution is correct and the alternative hypothesis would be: H1= The owner's distribution is incorrect We want to accept or refute the null using the significance of ? =.05, or 5%, to see what the probability of getting a result of this, or more extreme (p<.05), would be. ...read more.

Middle

Critical Chi-Square Value: Determine the Degrees of Freedom - We're taking 6 sums (6 days), so you may be tempted to say Degrees of Freedom =6, but if you have the first 5 values, you could find out the 6th, so we only have 5 Degrees of Freedom. We can say Degrees of Freedom = n-1 So, Our degree of freedom (D.F) is 5, our P value/significance is .05 or 5%, We can determine that our Critical chi-square value (?2c) is 11.07. Our D.F. is 5, so k=5 (magenta) If we continued the line, we would see that as the D.F. increases, the probability decreases. T-Tests The t- test is a method of statistical analysis used for comparison of sets of data. A t-test asks and answers the question, "Which set of data is higher?". The comparison must take into consideration the variability of data. Example: Hypothesis: Fluoride water prevents tooth decay. To test, the researcher looks at 5 communities that do have fluoride water, and 5 that do not. The dependent variable is the percent of the population with tooth decay, so a higher number is bad. ...read more.

Conclusion

sample one PLUS the Sample Variance of sample 2 SQUARED OVER number of observations in sample 2 So, for this experiment, this would look like: = 10.8/4.22 = 2.55924 t = 2.56 To use this t-value, we must compare it to the critical t-value for D.F. = 9. If our calculated value is > critical value in table, we can reject the null hypothesis. Assuming we use p< .05 or 5% (as in Chi-Square): Our calculated is 2.56, so Critical < Calculated We know that the null hypothesis of no difference between the means can be rejected, but that does not mean our hypothesis is either supported or rejected. We originally hypothesized that: Tooth decay is greater in communities without fluoride. Xf < Xnf From our data (% of population with tooth decay), we found that nf = mean of 22.4, f= mean of 11.6 We now know that 1. The means are significantly different; reject null 2. Difference between two means matches our hypothesis. Conclusion: We found that communities without fluoridated water had a greater percentage of the population with tooth decay than communities with fluoridation (t - 2.56, d.f.=9, p<.05) ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Psychology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Psychology essays

  1. Social Psychology - Blue Eyes vs. Brown Eyes Jane Elliot Film Analysis

    The simple act of discriminating against individuals based on physical characteristics instead of getting the time to know them personally can be seen as a social norm that has reoccurred throughout history, being passed down from generation to generation. 14.

  2. Psychology Critical Analysis Questions

    the other one is that information-processing models are likely to be very useful in explaining human behaviour. There are many beliefs that underpin these two basic assumptions. One is that mentality can be divided into a group of interrelated cognitive processes and every one of these can be studied separately.

  1. Psychology IB Abnormal Notes and Essay Plans

    do our thinking styles affect the levels of neurotransmitters in our brains? We do not know for sure. 4. There is a wealth of evidence to support the idea that (CBT) Cognitive Behavioural Therapy helps people to become well. This is a form of psychotherapy that challenges a personâs beliefs, helping them to rationalize distorted cognitions.

  2. A Long Way Gone: Memoirs of a Boy Soldier by Ishmael Beah--A Psychological Analysis ...

    did not get the reaction or recognition that they were looking for, made the boys angry. Perhaps this is because the staff did not identify the boys as killers as they themselves did. This is apparent in the staffs constant reminding that it was not their fault that they behaved as they did.

  1. Psychology IB Abnormality Notes

    necessarily deal with the real cause of a condition which could be socio-cultural or due to cognitive dissonance. Biological explanations are often considered too reductionist. 2. Also why is it that certain conditions are experienced more by one cultural group/gender than another? For example, Latah, Koro ? cultural bound syndromes.

  2. Anger management as a method of treating offenders

    Other benefits of this system are ease of administration, the use of immediate or frequent reinforcement (tokens) while teaching delayed gratification (holding tokens until trade-in time), lack of boredom or satiation for the prisoner due to the availability of a variety of back-up reinforcers, and lack of competition between other prisoners as they compete only against themselves.

  1. Of Dreams and Reality: A paper on hypnosis and dream analysis

    From another angle the social cognitive theory sheds some light on hypnosis in the sense you are tasked to play the role is necessitated of you during hypnosis and therefore you are able to see aspects of your personality which you would normally with your regular disposition.

  2. Psychological Analysis and the Psychology of Sales Technique

    One explanation of this is the self-perception theory. In 1972, Bem hypothesized that people infer their inner states from their behavior and the situation in which the behavior occurred, which basically means that people develop their attitudes by observing their own behavior and concluding what attitudes caused them.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work