STATS T2 Flashcards
standardised scores (z-scores)
Z-Score Formula
Falsifiability
capacity for some proposition, statement, theory or hypothesis to be proven wrong (through systematic empiricism) a basis provided by the null hypothesis
null hypothesis
states the contrary of the experimental or alternative hypothesis
falsifiable hypothesis
can be logically contradicted by an empirical test that can potentially be executed with existing technologies .
What is meant by dispersion/variability around the mean?
Determining how the scores relate towards the mean score
What are measures of variability?
Range Interquartile Range Standard deviation Sample variance if sd=0 so we square scores and then take the sum so negative scores become positive Absolute Mean Deviation SD but not squared which could= 0
What are the mean and standard deviation in the standard normal distribution?
mean=0 and sd=1 → z-score standard score specifying the amount of distance of the sd
What is the mean and the standard deviation of t-scores?
Mean = 50 SD= 100
What is meant by sampling error?
Chance difference = the way some statistics naturally varies from sample to sample = in that it wll always deviate from the parameter it is the random variability = standard deviation of the sampling distribution
What is the standard error of the mean?
The standard deviation / variability from the estimated parameter mean of the distribution
What is the purposes of the standard error?
It gives us an indication of just how much the sample statistic might differ across the samples. It’s like a z-score for all the potential differences we could observe but would not go against the finding
What are the logical steps of hypothesis testing?
Set up a research Hypothesis H1 Set up a null hypothesis H0 Get a sample and sample distribution of sample statistics (eg mean) und the H0 Calculate probability value of of sample statistic at least as large as the one obtained Reject or Fail to Reject H0
What’s the philosophical hypothesis of the null hypothesis?
M1-m2 =0 has been proposed by Fisher With the logic that we can always show that something is false
How do you calculate the IQR?
Order the scores Find the median location (N/2) Find the median of the upper and lower quartile N low /2; N high /2
What do d= 1 and d= .5 indicate?
That the effect the difference is either twice or half as large as the standard deviation
What are the absolute deviations from the mean?
X- Mean that’s why if we average and take the root of them we get the standard sample deviation
When you collect data from a sample, the sample variance is used to ?
make estimates or inferences about the population variance and comparing the variance of samples helps you assess group differences
How is the sample mean related to variance and standard deviation?
it is expanded on in the formulas for variance and standard deviation
Which five steps need to be taken to calculate the sample variance?
- The mean (∑ 𝑋 /N) 2. The Deviation from the mean X- (∑ 𝑋 /N) 3. Squared deviation from the mean (X- (∑ 𝑋 /N))^2 4. Find the sum for all scores and devide by N-1 5. Take the root to find the standard deviation or z-score
The standard deviation is more informative about the variability than the variance.
False
The standard deviation is expressed in larger units than the variance.
False because the root is taken
What does the standard deviation tell me?
how far, on average, a value lies from the mean which is why it is derived from the variance (square root)
Which graph describes a correct null hypothesis?
right
The p-value can be defined as
the probability of obtaining a significant result when the null hypothesis is true
